Through two large GOTV field experiments in two different elections, we investigate the spillover effect to other household members and family members outside the household. We mobilized young voters with cell phone text messages, a campaign tactic unlikely to be observed by other persons than the treated. The direct effect varied but approximately 30 percent spilled over to other persons in the household, even parents. The effects are subtle and we cannot with certainty establish that a spillover effect exists. However, we demonstrate, using Bayesian updating, that even an initial skeptic becomes close to convinced that the effect spills over. Our study provides evidence by suggesting that young individuals’ decision to vote affect other household members, including their parents, to do the same. When young voters live without their parents, we find no evidence of spillovers to parents, suggesting that households are more important than families ties for turnout contagion.