Dialectal differences are frequently cited by members of a majority group as their main means of identifying members of a minority ethnic group. However, existing stereotypes of minority language varieties and their speakers often suggest that social prejudices influence attitudes towards minority groups and their linguistic varieties. The present study examines the possible consequences of social prejudice on the attitudes towards Dominican Spanish in Puerto Rico. Dominican immigrants constitute the largest minority in Puerto Rico (Duany 2005). In spite of the linguistic similarities between Dominican and Puerto Rican Spanish (Lipski 1994) Dominican Spanish and its speakers have been found to be widely discriminated in Puerto Rico (Duany 2005; Mejia Pardo 1993). Relative to the Puerto Rican majority Dominican immigrants often have dark complexion, and less opportunities to access the educational system and a competitive work force (Duany 2005). These facts beg the question of whether and to what extent Puerto Ricans' attitudes towards Dominican Spanish truly are based on linguistic differences. The results of the verbal guise study imply that linguistic differences play an important part in the identification of national origin. Moreover, ratings on social and educational attributes of the guise speakers are indicative of the existence of prejudicial notions of socioeconomic and educational background. (Contains 10 notes, 1 figure, and 13 tables.)