This chapter considers the dynamics of birth control; in particular, placing birth control in the context of increasing state intervention into the household economy, sharpening divisions between men and women, and redefinition of the family. It addresses, as one critic put it, the ‘revolt against Nature’ whereby women first restricted their fertility. The chapter explores how the revolt was first suppressed, then coopted and redefined, emerging as a ‘functional adaptation’ producing the modern ‘small family’. Initially the spread of birth control practices produced a range of state responses, from hostile to sympathetic. During the 1900s pro-natalists successfully introduced legislative and administrative measures designed to make birth control more difficult; notably, suppressing advertisements for contraceptives and abortifacients, preventing imports of contraceptives, and regulating lying-in homes through registration and inspection. The changes which precipitated birth control in the first place became more extensive in the course of the early twentieth century; children became more dependent, women became more responsible for domestic labour.