When Lope de Vega (1562-1635) published his famous dramatic treatise, *Arte nuevo de hacer comedias* (New Art of Writing Plays), in 1609, he brought with him the experience of having written more than 480 plays and the endorsement of the aesthetic taste of the Spaniards of his time. In this *Arte nuevo*, in which the great Phoenix of Wits refers to the oral nature of his theater with terms such as hear, listener, audience, sonorous listening, silence, diction, and discourse, he outlined what constitutes an art in itself: that of writing plays in verse, adjusting the content to each type of stanza to create a thematic correspondence: "Adapt the verses prudently to the subjects you are dealing with; décimas are good for laments; the sonnet is well-suited to those who wait; romances are needed for narratives, although they shine brightly in octaves; tercets are for serious matters, and redondillas for love." These verses reveal a reflection stemming from the playwright's knowledge and sensitivity, which underpinned his concept of theatrical polymetry. The experience he had accumulated as a playwright had already borne great fruit in many ways, and one of them, as shown by the plays written before 1610, was having brought theatrical versification to such a level of development and innovation that it could only be further enriched and perfected. This is evident in his abundant output, but above all in his best plays, written during the 25 years he continued working. This book aims to offer some insights into this fundamental aspect of Lope de Vega's dramatic work: versification. Through the study of twenty plays, the intention is to demonstrate how, with his knowledge and genius, the comedic poet, supported by a rich cultural and literary heritage, created a system of composition to devise metrical procedures applied in the construction of his comedies.