Watermarks have played an important role in musicological manuscript studies in a number of different countries and musical traditions, but little work on watermarks has been done in Spanish music. In this study is combined independent work by two scholars who performed detailed manuscript studies of seventeenth-century sources in Spanish music archives at San Lorenzo del Escorial, Valladolid, Valencia, and elsewhere. Many different watermarks were discovered, but nine separate types emerge as a core group of watermarks common in this musical repertory. Additional study of manuscripts in the Archivo General in Simancas (the repository of court documents for the Hapsburg kings) and in booklets of printed poetic texts at the Biblioteca Nacional in Madrid demonstrates that these watermarks were very common in Spain during the period. Concordances of several of these watermarks have been identified by previous scholars, including Bayley, Briquet, Churchill, and Valls i Subirà. These nine watermarks commonly bear religious symbolism and a number of the papers appear to be of foreign origin (largely French or Italian) rather than Spanish. After briefly summarizing the state of papermaking in seventeenth-century Spain and the potential role of the couteau, or paper distributor, this presentation will conclude with brief consideration of each watermark, its appearance in Spanish music manuscripts, and some of its known concordances.