In the early seventeenth century, Spanish rulers were confronted by an avalanche of political satires. Beware the Poetry shows how these poetic libels helped articulate an early form of the public sphere, profoundly transforming political culture. Exploring a rich trove of mostly anonymous satirical works, together with newsletters, sermons, and plays, Javier Castro-Ibaseta reconstructs the experiences of Madrilenians during the reigns of Philip III and Philip IV. Castro-Ibaseta proposes an original theory of political publics that corrects approaches that assume early modern Spain's public sphere mirrored the politics of England or France. Instead, he shows that in Spain publicness was distinct because the satires-about the king's favorite, and even about the king himself-were consumed for pleasure and entertainment. They did not create political communities or stir rebellious movements. Read diachronically, the long, continuous, evolving collection of satires reveals not just the opinions of the poets but something far more difficult to reconstruct: the shifting demands, interests, uncertainties, and worldviews of the audience-that is, the structure and dynamics of Madrid's emerging public sphere. Applying an interdisciplinary approach of literary criticism and historical method, Beware the Poetry presents an exciting new take on politics and poetry during the period often referred to as the Spanish Decadence. It will be of special interest to scholars of early modern politics and Spanish literature and culture.