The Italian composer of operas, Giuseppe Verdi, relied heavily on plays of the Romantic Era as sources for opera librettos. Three such plays were from the Spanish Romantic School: El trovador and Simon Bocanegra by Antonio Garcia Gutierrez, and Don Alvaro o la fuerza del sino by Angel de Saavedra, el Duque de Rivas. The operas which Verdi composed using these plays as sources--Il trovatore, Simon Boccanegra, and La forza del destino--range in popularity from near zenith (Il trovatore) to near nadir (Simon Boccanegra). The study attempts to assess the suitability of the three Spanish dramas as source material for operas, and to determine if this suitability is correlated to each opera's popularity.