Both environmental protection and poverty alleviation are high on the international policy agenda for developing countries. We examine whether conditional environmental cash transfer programs contribute to the social protection of the beneficiaries, using data from a randomized controlled trial on reforestation, implemented in cooperation with the government of Burkina Faso. Randomly selected farmers were invited to undertake maintenance activities to increase the survival rate of trees that were planted on degraded forest lands. Compensation, in the form of monetary payments, varied with the number of trees still alive nine months after the tree planting. The timing of the conditional payments coincided with the lean season, when most farmers needed cash for food consumption and agricultural inputs. Six months after the transfers, the recipient households reported 12% higher food consumption expenditures compared to the control group, as well as a 35 and 60% reduction in, respectively, moderate and severe food insecurity. Our data indicate that the transfers received during the lean season were not only used to address immediate consumption needs but also to invest in crop and livestock production. The investments resulted in subsequent increases in agricultural outputs and income. We thus conclude that conditional environmental cash transfers, when paid in the lean season, can not only support consumption smoothing in the short run but can also improve livelihoods in the longer run. [ABSTRACT FROM AUTHOR]