Abstract: Marriage in Rome was monogamous; mating was polygynous. Powerful men in the Roman empire, as in other empires, probably had sex with more women. To make that case I look, first, at the Latin sources. Tacitus, Suetonius, and Cassius Dio suggest that Roman emperors, like other emperors, were promiscuous; that they had privileged access to other men's women; and that they sometimes had women procured for them. I look next at the modern studies. Literary, legal, and inscriptional data suggest that Roman men kept as many slaves as they could afford—often hundreds and sometimes thousands; that many of those slaves were women; and that slave women were often bought as breeders. They also suggest that masters, who had unrestricted sexual access to their slaves, were often the fathers. Some slave women's children were brought up with, and in the style of, legitimate children; they were freed young; and they were given wealth, position, and paternal affection.