The study findings suggests that adolescents' conceptions of the acceptability of their peers are related not only to sexual orientation but also to conformity with gender-based conventions. Both straight and gay or lesbian youth who were unconventional in their appearance and mannerisms were rated as less acceptable than individuals who conformed to gender-based conventions or those who participated in unconventional activities. For boys, the straight individual who was nonconforming in appearance was rated less acceptable than either the gay individual who conformed to gender-based norms or was nonconforming in the choice of activity preference. Participants were 109 male and 155 female 10th-grade and 12th-grade students who were attending a public high school in the suburb of a large midwestern city. Five of the boys and 10 of the girls identified themselves as gay/lesbian or bisexual. The first part of the questionnaire administered to the students solicited demographic information about gender, grade, ethnicity, and age. Part II assessed participants' evaluation of the acceptability of heterosexual and homosexual same-sex peers who varied in terms of their gender-base behaviors. Participants were presented with a series of descriptions of individuals who were either gay or straight and gender conforming or nonconforming in appearance/mannerisms, and/or choice of extracurricular activity. 2 tables, 2 figures, and 45 references