This paper expands on Kingsley Davis’s demographic thesis of change and re- sponse. Specifically, we consider the social context that accounts for the primacy of particular birth control methods that bring about fertility change during specific time periods. We examine the relevance of state policy (including national family planning programs), the international population establishment, the medical profession, organized religion, and women’s groups using case studies from Japan, Russia, Puerto Rico, China, India, and Cameroon. Some of these countries are undergoing the second demographic transition, others the first. Despite variations in context, heavy reliance on sterilization and/or abortion as a means of birth control is a major response in most of these countries. The key roles of the medical profession and state policy are discussed, along with the general lack of influence of religion and of women’s groups in these countries