The present study aims to characterize attitudes toward adoption by same-sex couples in a sample of Portuguese university students. Using a quasi-experimental design, participants (N = 500) were presented a vignette describing a couple adopting a child, manipulating couple sexual orientation and child gender. After reading the vignette, participants rated three different aspects of parental competence of the prospective parents (stability, abuse, and parental aptitude) and four different aspects of the future development of the adopted child (psychosocial adjustment, victimization, psychological disturbance, and normative sexuality). MANOVAs and follow-up ANOVAs were conducted in order to analyze the data. Participants expressed a heteronormative view of parenting, rating better the parental competence and child development of heterosexual, than of lesbian and gay parented families; however, they did not identify differences between lesbian and gay couples. Men expressed more negative attitudes than their female counterparts. Both men and women considered that a boy adopted by a gay couple would be less likely to have a normative sexuality than a girl in the same circumstances. By disentangling the effects of sexual orientation of prospective parents, gender of the adopted child, and gender of the participant, results of this study clearly contribute to a deeper understanding of attitudes toward lesbian and gay parent families. The role of gender is evident and its effect is explained taking into account sociological and psychological literature that connects gender, attitudes toward homo-sexuality, and adherence to hegemonic masculinity.