We study potential unintended effects of a large-scale national conditional cash transfer program. By exploiting time and geographic (district) variation in administrative data on the roll-out of Peru’s Juntos program, we investigate the effects on women’s fertility outcomes and behaviour. We find that women in districts included in the rollout are likely to see a reduction in fertility at the intensive margin (number of children), with no effect on the extensive margin (any childbearing) and that the district rollout is associated with a 5 percentage point increase in the take-up of modern contraception, effects that persist over time. These effects are not present among non-eligible groups within targeted districts. The persistence of these fertility and contraceptive use effects up to six years after the introduction of Juntos suggest that the program may have had long term transformational impacts on non-conditioned outcomes. By exploring various mechanisms, we do not find evidence that fertility preferences were affected by the program. Our findings rather suggest that Juntos empowers women in taking control over their fertility.