The oxytocin system, which is implicated in social cognition and behavior, is one potential biological pathway that influences an individual's capacity to extract positive emotions in social contexts. We tested whether several SNPs in two genes related to oxytocin reception (OXTR) and secretion (CD38) moderated positive emotion growth during a socially-focused intervention. For six weeks, a sample of mid-life adults participated in either loving-kindness or mindfulness training, and daily positive emotions were measured. DNA from blood was extracted to assess a set of SNPs within OXTR and CD38. Cumulative risk for OXTR and CD38 genes moderated positive emotion change during loving-kindness training. Lower-risk individuals experienced gains in daily positive emotions from loving-kindness training, while higher-risk individuals did not with either form of training. These findings are some of the first to shed light on how genetic differences in oxytocin processing influence the capacity to experience positive emotions in social contexts.