The early 20th century witnessed a revolution in contraceptive behaviour as the large Victorian family disappeared. This book offers a new perspective on the gender relations, sexual attitudes, and contraceptive practices that accompanied the emergence of the smaller family in modern Britain. It draws on a range of first-hand evidence, including over 190 oral history interviews, in which individuals born between 1900 and 1930 described their marriages and sexual relationships. It challenges many of the key conditions envisaged by demographers and historians as necessary for any significant reduction in average family size to take place. The book demonstrates that a massive expansion in birth control took place in a society in which sexual ignorance was widespread; that effective family limitation was achieved without the mass adoption of new contraceptive technologies; that traditional methods, such as withdrawal, abstinence, and abortion were often seen as preferable to modern appliances, such as condoms and caps; that communication between spouses was not key to the systematic adoption of contraception; and, above all, that women were not necessarily the driving force behind the prevention of pregnancy. Women frequently avoided involvement in family planning decisions and practices, whereas the vast majority of men in Britain from the interwar period onward viewed the regular use of birth control as a masculine duty. By allowing this generation to speak for themselves, the book produces a rich understanding of the startling social attitudes and complex conjugal dynamics that lay behind the changes in contraceptive behaviour in the 20th century.