Prevalence of obesity is rising in Latin America and increasingly affecting socially disadvantaged groups, particularly women. Conditional cash transfers are recently established welfare interventions in the region. One, Familias en Accion, transfers ∼20% of average monthly income to women in Colombia's poorest families. Previous work has found that families buy more food as a result. We tested the hypothesis that participation in Familias would be associated with increasing body mass index (BMI) in participating women.