A review of research belies many of the assumptions underlying the criminalization of homosexuality. While the majority shows a definite heterosexual orientation, there is evidence to suggest that a minority will develop a homosexual orientation that may be biologically influenced and that is unresponsive to attempts at heterosexual intercourse or social pressure to change. Assumptions that tolerance of homosexuality will result in increases in the number of homosexuals have not been supported by research in countries that have decriminalized homosexual relations. Similarly, the assumption that homosexuality is spread by seduction and proselytism, particularly of the young, is not supported by research. While homosexuals have been particularly vulnerable to sexually transmitted diseases, including AIDS, because of their more casual and promiscuous relationships, this vulnerability has no connection to sexual orientation. These findings lend no support that a homosexual orientation causes substantial harm. Nonetheless, public disapproval of homosexuality remains strong and favors criminalization, while laws criminalizing homosexual relations reinforce less tolerant attitudes. Social and legal policy demand a choice among conflicting values, balancing individual freedom against the wishes of society at large. To suppress homosexuality through criminalization is morally wrong, unnecessarily harsh, and impractical. A more humane policy is one of tolerance and nondiscrimination toward consensual sexual acts between adults. 131 references.