Until the late 1980s, the interest of many social scientists in sexual behaviour was restricted to the context of marriage. Malinowski (1929) and Mead (1949) are among the minority of anthropologists who regarded sexuality and social control of sexual expression as legitimate domains of study. Similarly, demographers have had a longstanding interest in sexual behaviour, but mainly as a determinant of fertility. Questions on post-natal abstinence have been a standard feature of demographic enquiries in Africa since the World Fertility Survey (WFS) in the 1970s. This information has proved crucial in attempts to understand reproductive regimes in that region (for example, Lestheaghe, 1989). Parenthetically, the custom of prolonged post-natal abstinence in West Africa has now emerged as a powerful influence on the extra-marital sexual activities of husbands with potentially serious consequences for disease transmission (Cleland et al., 1999).