This article advances the debate about costs and benefits of self-enhancement (the tendency to maintain unrealistically positive self-views) with a comprehensive meta-analytic review (299 samples, N = 126,916). The review considers relations between self-enhancement and personal adjustment (life satisfaction, positive affect, negative affect, depression), and between self-enhancement and interpersonal adjustment (informant reports of domain-general social valuation, agency, communion). Self-enhancement was positively related to personal adjustment, and this relation was robust across sex, age, cohort, and culture. Important from a causal perspective, self-enhancement had a positive longitudinal effect on personal adjustment. The relation between self-enhancement and interpersonal adjustment was nuanced. Self-enhancement was positively related to domain-general social valuation at 0, but not long, acquaintance. Communal self-enhancement was positively linked to informant judgments of communion, whereas agentic self-enhancement was linked positively to agency but negatively to communion. Overall, the results suggest that self-enhancement is beneficial for personal adjustment but a mixed blessing for interpersonal adjustment.