The present description of the phonemes of Costa Rican Spanish is offered primarily for comparison with Castilian Spanish. Attention is directed especially to Tomás Navarro Tomás, Manual de pronunciación española (Madrid, 1932), and George L. Trager, The phonemes of Castilian Spanish, TCLP 8.217–22 (1939); Trager's article is essentially a phonemic restatement of Navarro Tomás' larger work. It is hoped that the present study will lead also to further comparisons, on the phonemic level, with other modern Spanish dialects, American and European.