Brazil's rapid fertility decline occurred during a period of extraordinarily intense social change, which encompassed times of both rapid economic growth and economic crisis. The widespread institutional changes introduced by the military regime in the mid-1960s as part of its efforts to induce rapid modernization had several unintended impacts on the motivation to control fertility and on the ability to do so. Several characteristics of Brazil's fertility decline warrant highlighting. First, high rates of abortion and sterilization are the primary means by which the decline was achieved. This outcome is partly attributable to the interplay of attitudes, policies, and changing agendas of key social actors, which tended to limit the practical availability of other effective methods. The increased motivation to control fertility is traceable to the indirect effects of institutional changes in the areas of health and social security. The strong influence of the mass media on social behavior, including reproductive behavior, is also noteworthy.