A madrigal is a type of secular vocal music composition, written during the Renaissance and early Baroque eras. Throughout most of its history it was polyphonic and unaccompanied by instruments, with the number of voices varying from two to eight, but most frequently three to six. The earliest examples of the genre date from Italy in the 1520s, and while the center of madrigal production remained in Italy, madrigals were also written in England and Germany, especially late in the 16th and early in the 17th centuries. Unlike many other strophic forms of the time, most madrigals are through-composed, with music being written to best express the sentiment of each line of a poetic text. The madrigal originated in part from the frottola, in part from the resurgence in interest in vernacular Italian poetry, and also from the influence of the French chanson and polyphonic style of the motet as written by the Franco-Flemish composers who had naturalized in Italy during the period. The madrigal is related mostly by name alone to the Italian trecento madrigal of the late 13th and 14th centuries.
The madrigal was the most important secular form of music of its time. It reached its fullest development in the second half of the 16th century, losing its importance in the early 17th century, when forms such as the solo song became more popular. After the 1630s it merged with the cantata and the dialogue, and the solo madrigal was replaced by the aria due to the rise of opera as an important genre.
In the early 16th century, several humanistic trends converged which allowed the madrigal to form. First, there was a reawakened interest in use of Italian as a vernacular language. Poet and literary theorist Pietro Bembo edited an edition of Petrarch, the great 14th century poet, in 1501, and later published his theories on how contemporary poets could attain excellence by imitating Petrarch, and by being carefully attentive to the exact sounds of words, as well as their positioning within lines. The poetic form of the madrigal, which consisted of an irregular number of lines of usually 7 or 11 syllables, without repetition, and usually on a serious topic, came into being as a result of Bembo's influence.   
Second, Italy had long been a destination for the superbly-trained composers of the Franco-Flemish school, who were attracted by the culture as well as the employment opportunities at the aristocratic courts and ecclesiastical institutions – Italy was, after all, the center of the Roman Catholic Church, the single most important cultural institution in Europe. These composers had mastered a serious polyphonic style suitable for setting sacred music, and also were familiar with the secular music of their homelands, music such as the chanson, which differed considerably from the lighter Italian secular styles of the late 15th and very early 16th centuries. 
Third, printed secular music had become widely available in Italy due to the recent invention of moveable type and the printing press. The music being written and sung, principally the frottola but also the balleta, canzonetta, and mascherata, was light, and typically used verses of relatively low literary quality. These popular music styles used repetition and soprano-dominated chordal textures, styles considerably more simple than those used by most of the resident composers of the Franco-Flemish school. Literary tastes were changing, and the more serious verse of Bembo and his school needed a means of musical expression more flexible and open than was available in the frottola and its related forms.  
The first madrigals were written in Florence, either by native Florentines or by Franco-Flemish musicians in the employ of the Medici. The madrigal did not replace the frottola right away; during the transitional decade of the 1520, both frottole and madrigals (though not yet in name) were written and published. The earliest madrigals were probably those by Bernardo Pisano, in his 1520 Musica di messer Bernardo Pisano sopra le canzone del Petrarcha, which was also the first secular music collection ever printed containing only the works of a single composer. While none of the pieces in the collection use the name "madrigal", some of the compositions are settings of Petrarch, and the music carefully observes word placement and accent, and even contains word-painting, a feature which was to become characteristic of the later madrigal. 
The first book of madrigals labeled as such was the Madrigali de diversi musici: libro primo de la Serena of Philippe Verdelot, published in 1530 in Rome. Verdelot, a French composer, had written the pieces in the late 1520s, while he lived in Florence. He included music by both Sebastiano and Costanzo Festa, as well as Maistre Jhan of Ferrara, in addition to his own music. In 1533 and 1534 he published two books of four voice madrigals in Venice; these were to become extremely popular, and indeed they were, in their 1540 reprint, one of the most widely printed and distributed music books of the first half of the 16th century. They sold so well that Adrian Willaert made arrangements of some of these works for single voice and lute in 1536. Verdelot published madrigals for five and six voices as well, with the collection for six voices appearing in 1541.
Particularly popular was the first collection of madrigals by Jacques Arcadelt. Originally published in Venice, in 1539, it was reprinted throughout Europe for many years after, becoming the most often reprinted madrigal book of the entire era. Stylistically, the music in both Arcadelt's and Verdelot's books was more akin to the French chanson than either the Italian frottola or the sacred music of the time, such as the motet. This may be unsurprising considering that the native language of both Arcadelt and Verdelot was French, and both had written chansons themselves when in their homeland; however, they were carefully attentive to text setting, in keeping with the ideas of Bembo, and they through-composed the music, writing new music for each line of text, rather than using the refrain and verse constructions that were common in French secular music.
While the madrigal was born in Florence and Rome, by mid-century the centers of musical activity had moved to Venice and other cities. The mercenaries of Charles V sacked Rome in 1527, and a period of related political turmoil in Florence, culminating in the Siege of Florence (1529-30), in which Verdelot himself may have perished, reduced that city's significance as a musical center. In addition, Venice was Europe's center of music publishing; the grand Basilica of St. Mark's was just beginning the period in which it attracted musicians from all over Europe; and Pietro Bembo himself had returned to Venice in 1529. Adrian Willaert and his associates at St. Mark's – younger men such as Girolamo Parabosco, Jacques Buus, Baldassare Donato, Perissone Cambio, and Cipriano de Rore – were the primary representatives of madrigal composition at mid-century. Willaert preferred more complex textures to Arcadelt and Verdelot; often his madrigals were similar to motets, with their polyphonic language, although he varied texture between homophonic and polyphonic passages as necessary to highlight the text. For verse he used Petrarch in preference to Petrarch's 16th-century imitators; many of his madrigals set Petrarch's sonnets.  
Cipriano de Rore was the most influential of the mid-century madrigalists after Willaert. While Willaert was restrained and subtle in his text setting, striving more for homogeneity than sharp contrast, Rore was one to experiment. He used extravagant rhetorical gestures, including word-painting and unusual chromatic relationships, a trend encouraged by visionary music theorist Nicola Vicentino.  It was from Rore's musical language that "madrigalisms", so distinctive of the genre, first came about; and it was also with Rore that five-voice texture became the standard.
The later history of the madrigal begins with Rore. All of the different trends in madrigal composition, which by the early 17th century had diverged into many different forms, are present in embryonic form in Rore's enormously influential output. 
Many thousands of madrigals were written in Italy in the 1550s; the entire repertoire is yet to be studied exhaustively. Some famous names of the period, besides Rore, are Palestrina, who wrote some secular music early in his career; the young Orlande de Lassus, who wrote many well-known examples, including the highly experimental and chromatic Prophetiae Sibyllarum, and who, on moving to Munich in 1556, began the history of madrigal composition outside of Italy; and Philippe de Monte, the most prolific of all madrigal composers, whose first publication dates from 1554.  In style, the madrigals of the 1550s varied from the conservative and elegant style of Palestrina and some of the others working in Rome, to the highly chromatic and expressive work by Lassus, Rore, and others working in the cities of northern Italy.Late in the 16th century, while "classic" madrigals continued to be written throughout Italy, different styles of madrigal composition developed somewhat independently in different geographic areas. In Venice, composers such as Andrea Gabrieli continued to write madrigals in the classic tradition, but with the bright, open, polyphonic textures for which he was famous in his motets and other works. At the court of Ferrara, the presence of three uniquely gifted female singers – the concerto delle donne – attracted a group of composers who wrote highly ornamented madrigals, often with instrumental accompaniment, to be performed by members of this group. These composers included Luzzasco Luzzaschi, Giaches de Wert, and Lodovico Agostini, but the fame of the group was so widespread that many composers visited Ferrara both to hear and write for them, and in some cases founded similar groups of their own in other cities (for example, the Medici attempted to imitate the group in Florence, and had Alessandro Striggio write madrigals in a style like Luzzaschi's).  Rome, the ostensibly conservative center of the Roman Catholic Church, was itself the home of one of the most famous madrigal composers of the era, Luca Marenzio. Marenzio came closest to unifying all the different stylistic currents of the time, writing madrigals which attempted to capture every nuance of emotion in the poems using every musical means then available. Marenzio wrote over 400 madrigals during his short life.
Yet another trend in madrigal composition after mid-century was the re-incorporation of lighter elements into the form, which had been predominantly a serious genre since its inception. Where verse by Petrarch had been the standard, and themes of love and longing and death had been typical, by the 1560s composers had begun bringing back elements of some lighter Italian forms, such as the villanella, with their dancelike rhythms and verses on carefree subjects. Some of the composers who wrote in this manner included Marc'Antonio Ingegneri, the teacher of Monteverdi, Andrea Gabrieli, and Giovanni Ferretti. The canzonetta was a specific offshoot of the madrigal in this vein.
Especially during the late 16th century, composers were ingenious in their use of so-called "madrigalisms" - passages in which the music assigned to a particular word expresses its meaning, for example, setting riso (smile) to a passage of quick, running notes which imitate laughter, or sospiro (sigh) to a note which falls to the note below. This technique is also known as "word-painting." While it originated in secular music, it made its way into other vocal music of the period. While this mannerism is a prominent feature of madrigals of the late 16th century, including both Italian and English, it encountered sharp criticism from some composers. Thomas Campion, writing in the preface to his first book of lute songs 1601, said of it: "... where the nature of everie word is precisely expresst in the Note ... such childish observing of words is altogether ridiculous."
The change in the social function of the madrigal at the end of the 16th century contributed to its development into new dramatic forms. Since its invention, it had served two principal roles: as a pleasant private entertainment for small groups of skilled amateur musicians; and as an adjunct to large ceremonial public performances. The first use, the private one, was by far the most common throughout the life of the madrigal, and it was through these enthusiastic gatherings of amateurs that the madrigal acquired its fame. However, in the last two decades of the century, virtuoso professional singers began to replace amateurs, and composers wrote music for them of greater dramatic force. Not only was this music harder to sing, but the sentiments expressed tended to require soloists rather than equal members of an ensemble in order to be dramatically convincing. Also during this period a division between performers and passive audiences – not the large audiences present at a public ceremonial spectacle, as seen earlier in the century, but relatively small, intimate gatherings, with performers and listeners, a situation recognizably modern – began to be seen, especially in such progressive cultural centers as Ferrara and Mantua. Much of what was once expressed in a madrigal in 1590, could twenty years later be expressed by an aria in the new form of opera; however, the madrigal continued to live on into the 17th century, in several forms, including old-style madrigals for many voices; a solo form with instrumental accompaniment; and the concertato madrigal, of which Claudio Monteverdi was the most famous practitioner.
Naples was the home of the notoriously murderous nobleman Carlo Gesualdo, who not only killed his wife and her lover in flagrante delicto but wrote some of the most extravagantly expressive and harmonically experimental music prior to the 19th century. Gesualdo's style followed directly from Luzzaschi's, and he named the older composer as his mentor: the two worked together at Ferrara in the early 1590s, giving Gesualdo ample opportunity to absorb the chromaticism and textural contrasts of the Ferrarese, including Luzzaschi and Alfonso Fontanelli. Gesualdo published six books of madrigals during his lifetime, as well as some sacred music in madrigalian style (for example the Tenebrae Responsories of 1611). No one followed Gesualdo down this path of mannerism and extreme chromaticism, although composers such as Antonio Cifra, Sigismondo d'India, and Domenico Mazzocchi selectively used some of his techniques.  
Of all the composers of madrigals of the late 16th century, none was as central a figure as Claudio Monteverdi, who was often credited as the principal actor in the transition from Renaissance music to Baroque music. In his long career, he wrote nine books of madrigals, which showed the transition from the late 16th-century polyphonic style to the monodic and concertato style, accompanied by basso continuo, of the early Baroque. As expressive as Gesualdo, he avoided the extremes of chromaticism employed by that composer and instead focused on the dramatic possibilities inherent in the form. His fifth and sixth books include not only polyphonic madrigals for equal voices in the manner of the late 16th century, but also madrigals with parts for solo voice accompanied by continuo; additionally these works make use of unprepared dissonances and recitative-like passages, foreshadowing the eventual absorption of the solo madrigal into the aria. These madrigals also show the influence of monody, developing at the same time: Manfred Bukofzer called the development of the recitative-like 'stile rappresentativo' around 1600 as "the most important turning point in the entire history of music." To Monteverdi the words must be "the mistress of the harmony", and he explained this doctrine in his preface to his Fifth Book of Madrigals with his coinage of the term 'seconda pratica', in response to the fierce criticism of Giovanni Artusi, who defended the polyphonic style of the 16th century with its controlled dissonance and equal voice parts, and attacked the "barbaric" new style. 
During the first decade of the 17th century the madrigal moved away from the old ideal of an a cappella vocal composition for equally balanced voices, into a piece for one or more voices with instrumental accompaniment. The soprano and bass line became more important to the texture than the inner voices, if they existed at all as independent parts; functional tonality began to develop; composers treated dissonance more freely than before; and dramatic contrasts between groupings of voices and instruments became increasingly common. In the 17th century madrigal, two separate trends can be identified: the solo madrigal, which involved a solo voice with basso continuo, and madrigals for two or more voices, also with basso continuo. In addition, some composers continued to write ensemble madrigals in the older style, especially in England.  While the harmonic and dramatic changes in the madrigal around 1600 may seem abrupt, the addition of instruments was not a new thing. Instrumental performance of madrigals had already been widespread for much of the 16th century, either in arrangements or in performances mixed with singers. As madrigals had originally been largely designed for performance by groups of talented amateurs, without a passive audience, instruments were also commonly used to fill in for missing parts. Instrumentation during the period was rarely specified; indeed Monteverdi indicated in his fifth and sixth book of madrigals that the basso seguente, the instrumental bass part, was optional in the ensemble madrigals. The most commonly used instruments for playing the bass line and filling in any inner parts, at this time, were the lute, theorbo, chitarrone, and harpsichord. 
One of the prominent composers of madrigals in the solo with continuo style, related to monody and descended directly from the experimental music of the Florentine Camerata, was Giulio Caccini, who published the first collection of solo madrigals with his Le nuove musiche in 1601/2. The point was anti-contrapuntal: Caccini and the Camerata believed that the words needed to be heard above all else, and polyphonic, evenly balanced voices easily obscured intelligibility. After Caccini, composers such as Marco da Gagliano, Sigismondo d'India, and Claudio Saracini published collections of their own; while Caccini's music was almost entirely diatonic, some of these later composers, particular d'India, wrote their solo madrigals in a more experimental chromatic idiom. Monteverdi himself wrote only one solo madrigal, which he published in his Seventh Book of Madrigals in 1619. While it uses only one singing voice, it employs three separate groups of instruments – a considerable advance from the simple voice and basso continuo compositions of Caccini at the turn of the century.
Solo madrigals in the monodic style began to go out of fashion shortly before 1620, to be replaced by the aria. The last book of solo madrigals which did not contain any arias appeared in 1618; that was also the first year in which a group of arias was published which contained no madrigals. After that date arias outnumbered madrigals, and both Saracini and d'India, previously prolific composers of solo madrigals, ceased publishing them in the early 1620s.
Two collections of the late 1630s serve as a summation of late madrigal practice. Domenico Mazzocchi's 1638 book splits madrigals into continuo and ensemble works specifically intended to be performed a cappella; Mazzocchi's instructions are precise, and he even includes, for the first time in any printed music collection, symbols for crescendo and decrescendo. However, these madrigals were not intended for performance so much as study, and as such show that the form was being viewed in retrospect. Monteverdi's Book Eight, of the same year, contains some of the most famous madrigals of the entire epoch, including the enormous Combattimento di Tancredi e Clorinda, a dramatic composition much like a secular oratorio. Among other innovations in this work is the stile concitato – the "stile of agitation", which uses, among other things, string tremolo. The pieces in Monteverdi's Book Eight, written over at least two decades, show just about every development in the madrigal since 1600.
Eventually the madrigal vanished as an independent form. The solo madrigal was supplanted by the aria and solo cantata; the ensemble madrigal by the cantata and dialogue. By 1640 few madrigals were still being published, and opera had become the predominant dramatic musical form.
See main article: English Madrigal School. In England, the madrigal became hugely popular after the publication of Nicholas Yonge's Musica Transalpina in 1588, a collection of Italian madrigals fitted with English translations; this publication initiated an entire school of madrigal composition in England. The unaccompanied madrigal survived longer in England than in the rest of Europe. There, composers continued to produce works in the late-16th century style of the genre after the form had gone out of fashion on the Continent.
Madrigals influenced secular music in many other parts of Europe, and in some areas composers wrote actual madrigals, either in Italian or in their own languages. The amount of influence was roughly inversely proportional to the strength of the local secular musical tradition: for example France, which had the robust and sophisticated form of the chanson during the 16th century, never adopted the madrigal – they didn't need it. However some French composers, especially those who had been to Italy, used madrigalian techniques in their writing. These composers included cosmopolitan figures such as Orlande de Lassus, who wrote in at least four languages, as well as Frenchmen such as Claude Le Jeune.
The Netherlands was a major center of music publishing, and since Italian madrigals were easily available from publishing houses, some native composers wrote works either in influence or imitation. Cornelis Verdonck, Hubert Waelrant, and Jan Pieterszoon Sweelinck all composed madrigals in Italian.
Germany was the home of several prolific composers of madrigals, including Lassus (in Munich) and Philippe de Monte (Vienna), the most prolific madrigal composer of all. Many Germans had gone south to study in Italy, particularly with the Venetians; Hans Leo Hassler studied with Andrea Gabrieli, and Heinrich Schütz with Monteverdi. Each brought back to Germany what they learned, and wrote madrigals or madrigalian pieces both in Italian and German. Musicians from the courts of Denmark and Poland also studied the Italian style either in their home countries or in Italy; Marenzio himself had worked in Poland near the end of his life.
In early 18th century England, singing of madrigals was revived by catch and glee clubs, and later by the formation of the Madrigal Society in 1741, which still meets today. As a result of the printing and singing of madrigals, particularly English ones, the madrigal became the best-known form of Renaissance secular music in England in the 19th century, even before the rediscovery of works by composers such as Palestrina.
Choral groups continue to sing madrigals in the present day; in the United States they are particularly popular with high school and college groups. In the U.S., madrigal choirs often sing in the context of a madrigal dinner which may also include a play, Renaissance costumes, and instrumental chamber music. The focus is generally on the repertory of the English Madrigal School.
For either solo voice or vocal ensemble, but always with basso continuo and often groups of other instruments:
Some 60 madrigals of the English School are published in The Oxford Book of English Madrigals