Many studies have suggested that unmarried adolescent childbearing is becoming a social problem in many countries of sub-Saharan Africa, because it tends to lead to school drop-outs, illegal abortions, and child abandonment. To date, the motivations for adolescent childbearing remain poorly understood. One point of view is that unmarried adolescent childbearing results from a breakdown of social controls by the elders over young people. Others have argued that adolescent childbearing is a form of rational adaptation; a means to achieve a specific goal. For example, girls may choose to become pregnant if they believe that a pregnancy will lead to marriage. In this paper adolescent sexual activity and premarital childbearing in seven sub-Saharan African countries are examined with data from Demographic and Health Surveys. In a first section, the impact of socio-economic indicators on adolescent sexual and reproductive behaviour is examined; a subsequent section is focused on the motivation for different types of adolescent behaviour.