Modern people presume ‘sex’ to be a function of biology and ‘sexuality’ to be a fundamental aspect of identity. Since Buddhist monks and nuns are celibate by definition, many assume a uniform sex-negativity in Buddhism. But Buddhist teachers and practitioners have thought about, talked about, and performed sex in many modes beyond the negative. Buddhism, a tradition originating in ancient India but straddling tens of centuries and multiple cultural, national, and linguistic boundaries, provides many opportunities for reflection on the putative universality of biological ‘sex’, and the theorized modernity of ‘sexuality’. How, when, and why do Buddhists have sex? Do Buddhists have a sexuality? This article employs the logical formula of the tetralemma to explore the topics of sex and sexuality in various Buddhist traditions, challenge the supposed sex-negativity of Buddhism, and question the applicability of ‘sexuality’ in its modern usage as a term of critical analysis in Buddhist contexts.