Coital frequency is at the heart of the debate over low marital fertility in pretransition China. This study argues that coital frequency in contemporary China is indicative of sexual behavior in an earlier era. Frequency of intercourse is low in China relative to Europe, a natural outgrowth of a traditional family system and related sexual culture only partially transformed by a century of family revolution. Customary sexual behaviors and breastfeeding practices together shaped the Chinese historical fertility regime as they did the European. As explanations for China's low marital fertility, these proximate determinants leave little scope for the operation of fecundity-reducing malnutrition on the one hand, or deliberate fertility control on the other. The fertility regimes of other pretransition agrarian societies more closely resemble China's than Europe's, seeming to confirm a pattern of European demographic exceptionalism.