Is it advantageous to move first in a negotiation? Should one make an ambitious first offer? Does first-offer magnitude impact final outcomes? While a plethora of research suggests that these three questions can be answered affirmatively with a remarkable robustness across cultures, countries, and contexts, recent findings are not unequivocally advantageous and range from positive to null to even negative effects. Despite decades of research, a comprehensive meta-analysis of economic first-offer effects and their moderators remains missing. Our preregistered meta-analysis with the robust variance estimation (RVE) approach conceptualized and quantified three empirical first-offer effects on negotiation outcomes: (1) a first-mover advantage (g = 0.49), (2) a first-offer magnitude effect (g = 1.30), and (3) a positive offer-outcome correlation (r = 0.53; g = 1.51). Overall, effect sizes were highly heterogeneous and moderated by publication, sample, negotiation, and first offer characteristics. We discuss theoretical and applied implications for the negotiation literature.