The current article aimed to find psychometric evidences in the Internal and External Motivation to Respond without Prejudice Scale (Plant & Devine, 1998) taking into account two target-groups: gays and lesbians. Two studies were carried out. In Study 1 participants were 234 subjects from the general population of Joao Pessoa-PB, with mean age of 26 years old, most of them female (54.3%) and heterosexual (95%). They answered the gay version of the Internal and External Motivation to Respond without Prejudice Scale (IEM Scale). Confirmatory factor analyses indicated that the two-factor model (AGFI = .94, CFI = .98, and RMSEA = .05) is the most adequate. Cronbach's Alphas for the factors were .74 (internal motivation) and .76 (external motivation). In Study 2 participants were 202 subjects of general population from the same city, with mean age of 25 years old, most of them female (60.9%) and heterosexual (95%). They answered the lesbian version IEM Scale. Corroborating the previous study, a two-factor model was more adequate (AGFI = .90, CFI = .95, and RMSEA = .08). Cronbach's Alphas for the two factors were .71 (internal motivation) and .84 (external motivation). Complementary evidences of the construct validity were also presented. In conclusion, the results support the psychometric adequacy (factorial validity, convergent-discriminant validity, and reliability) of the IEM Scale suggesting it can be used in future studies about prejudice toward gays and lesbians.