Homosexuality in ancient Rome is a subject of research and scholarly debate. Homosexuality in ancient Rome differed markedly from the contemporary West. Latin lacks words that would precisely translate "homosexual" and "heterosexual". The primary dichotomy of ancient Roman sexuality was active / dominant / masculine and passive / submissive / feminine. Roman society was patriarchal, and the freeborn male citizen possessed political liberty (libertas) and the right to rule both himself and his household (familia). "Virtue" (virtus) was seen as an active quality through which a man (vir) defined himself.

The conquest mentality and "cult of virility" shaped same-sex relations. Pederasty between males was documented, and such relationships were condoned as long as the Roman man took an active/dominant role and passive younger male partner was not a freeborn youth/boy. Acceptable male partners were slaves and former slaves, prostitutes, and entertainers, whose lifestyle placed them in the nebulous social realm of infamia, so they were excluded from the normal protections afforded to a citizen even if they were technically free. Freeborn male minors were off limits at certain periods in Rome.

Same-sex relations among women are far less documented and, if Roman writers are to be trusted, female homoeroticism may have been very rare, to the point that Ovid, in the Augustine era describes it as "unheard-of". However, there is scattered evidence—for example, a couple of spells in the Greek Magical Papyri—which attests to the existence of individual women in Roman-ruled provinces in the later Imperial period who fell in love with members of the same sex.

During the Republic, a Roman citizen's political liberty (libertas) was defined in part by the right to preserve his body from physical compulsion, including both corporal punishment and sexual abuse. Roman society was patriarchal (see paterfamilias), and masculinity was premised on a capacity for governing oneself and others of lower status. Virtus, "valor" as that which made a man most fully a man, was among the active virtues. Sexual conquest was a common metaphor for imperialism in Roman discourse, and the "conquest mentality" was part of a "cult of virility" that particularly shaped Roman homosexual practices. Roman ideals of masculinity were thus premised on taking an active role that was also, as Craig A. Williams has noted, "the prime directive of masculine sexual behavior for Romans". In the late 20th and early 21st centuries, scholars have tended to view expressions of Roman male sexuality in terms of a "penetrator-penetrated" binary model; that is, the proper way for a Roman male to seek sexual gratification was to insert his penis into his partner. Allowing himself to be penetrated threatened his liberty as a free citizen as well as his sexual integrity.

It was socially acceptable for a freeborn Roman man to want sex with both female and male partners, as long as he took the penetrative role. Outside of marriage a man was supposed to act on his desires with only slaves, prostitutes (who were often slaves), and the infames. It was immoral to have sex with another freeborn man's wife, his marriageable daughter, his underage son, or with the man himself; sexual use of another man's slave was subject to the owner's permission. Lack of self-control, including in managing one's sex life, indicated that a man was incapable of governing others; too much indulgence in "low sensual pleasure" threatened to erode the elite male's identity as a cultured person.

Homoerotic themes are introduced to Latin literature during a period of increasing Greek influence on Roman culture in the 2nd century BC. Greek cultural attitudes differed from those of the Romans primarily in idealizing eros between freeborn male citizens of equal status, though usually with a difference of age (see "Pederasty in ancient Greece"). An attachment to a male outside the family, seen as a positive influence among the Greeks, within Roman society threatened the authority of the paterfamilias. Since Roman women were active in educating their sons and mingled with men socially, and women of the governing classes often continued to advise and influence their sons and husbands in political life, homosociality was not as pervasive in Rome as it had been in Classical Athens, where it is thought to have contributed to the particulars of pederastic culture.

In the Imperial era, a perceived increase in passive homosexual behavior among free males was associated with anxieties about the subordination of political liberty to the emperor, and led to an increase in executions and corporal punishment. The sexual license and decadence under the empire was seen as a contributing factor and symptom of the loss of the ideals of physical integrity (libertas) under the Republic.

Love or desire between males is a very frequent theme in Roman literature. In the estimation of Amy Richlin, out of the poems preserved to this day, those addressed by men to boys are as common as those addressed to women.