Artefactual and lab experiments are increasingly utilized to study variation in preferences across groups and the relationship between preferences and economic outcomes. Social learning across experimental sessions is rarely considered within the literature and not well understood, but may alter the validity of such studies. In this paper I provide evidence of social learning during a large implementation of public goods games in the Rusizi district in Rwanda. Contact with previous participants led to significant behavioral change, despite theoretical predictions that such contact will have no effects. Using GPS data on over 1,700 participants across 150 villages I document an increasing pattern of contributions in public goods games over space and time. An investigation of the mechanism behind the effect finds that it is strongest for individuals who exhibit conditionally cooperative behavior, suggestive that contact involves social learning about cooperative norms.