Marithelma Costa was born in San Juan, Puerto Rico. She studied Philosophy at the University of Puerto Rico and at the Universidad Autónoma de Madrid (M.A. or Licenciatura, 1979); Spanish Philology and Literature at Columbia University (M.A. 1980) and at the Graduate Center of the City University of New York, where she got her Ph.D. (1988).
She has taught at Université de Paris-13, where she participated at the Séminaire d'Etudes Médiévales (1997) and at Lehman College (1980-1988). Currently she is a member of the faculty of Hunter College and the Graduate Center, where she teaches courses on Spanish Balladry and Poetry of the Cancionero.
Her research interests are twofold: Spanish medieval poetry and 20th-century Caribbean literature. She studies 15th-century poetry, particularly the works of the "converso" Antón de Montoro, and has published his complete works: Antón de Montoro. Poesía completa (Cleveland State U. Press, 1990). She has also written a book on the poet's social and economic background: Bufón de palacio y comerciante de ciudad. La obra del poeta cordobés Antón de Montoro (Córdoba: Diputación Provincial, 2001). Recently she published, with Editorial Plaza Mayor, two critical editions of Enrique Laguerre's novels: La llamarada (2002) and La resaca (2009). She has also written several articles on the Hispanic poets of New York.
In addition, Professor Costa has worked on several books of interviews: Enrique Laguerre. Una conversación (San Juan: Plaza Mayor, 2000), Kaligrafiando: Conversaciones con Clemente Soto Vélez (San Juan: Ed. de la Universidad de Puerto Rico, 1990: with Alvin Figueroa) and Las dos caras de la escritura. Conversaciones con M. Benedetti, M. Corti, U. Eco et al.) San Juan: Ed. Sin Nombre/Ed. de la Universidad de Puerto Rico, 1988: with Adelaida López).
She has published numerous articles on medieval and contemporary poetry which have appeared in American, Mexican, Argentinian, Colombian, Puerto Rican, French and Spanish, scholarly journals and collective volumes, among them, Cahiers de Linguistique Médievales, Filología, Medievalia, La Torre, Hispamérica, Anuario Medieval, Revista de Occidente. She has lectured at many universites in the United States, Puerto Rico, France and Spain.
She has also published three books of poetry: Diario OiraiD (New York: OLLANTAY Press, 1997), De tierra y de agua (San Juan: Instituto de Cultura Puertorriqueña, 1988) and De Al'vión (New York: Lautaro Editorial Ibero-Americana, 1987), and the novel Era el fin del mundo (San Juan: Plaza Mayor, 1999).
Professor Costa has received several grants and awards, among them the American Council for Learned Societies Fellowship, The Program for Cultural Cooperation Between Spain's Ministry of Culture and States Universities Grant, the CUNY Collaborative Incentive Research Grant, the American Philosophical Society Award, and a National Endowment for the Humanities, We The People grant. In 1996 she became a Faculty of the City University of New York Honoree and was granted an Access to Excellence award.