Gender differences in the initiation of negotiation have been suggested to reinforce unequal distributions of resources between men and women. Because previous research had yielded heterogeneous results, the authors conducted a meta-analysis investigating gender differences in initiating negotiation. On the basis of social role theory, they hypothesized that women are less likely to initiate negotiations than men, but also that the effect varies depending on characteristics of the immediate negotiation situation and the wider societal context. The meta-analysis comprised 55 effect sizes with 17,504 individuals, including both students and employees. A random-effects model confirmed that women were indeed less likely to initiate negotiations than men (g = 0.20). Additional moderator analyses, tested with mixed-effects models and metaregressions, revealed that gender differences were smaller when situational ambiguity regarding the appropriateness of negotiating was low rather than high as well as when situational cues were more consistent with the female gender role than with the male gender role. Gender differences decreased by year of publication (from 1977 to 2016) but were unrelated to the degree of gender inequality in the countries in which the studies were conducted. The authors conclude that gender differences in the initiation of negotiation exist, but they are small and context-bound. Finally, they discuss mechanisms that alter the gender difference with a particular focus on potential starting points for practical interventions. Public Significance Statement The present meta-analysis shows that overall women are less likely to initiate negotiations than men. While certain situational characteristics attenuate the gender difference (e.g., individuals are explicitly prompted to negotiate), others reinforce the gender difference (e.g., individuals are in doubt whether negotiating is appropriate). Addressing gender differences in the initiation of negotiation might ultimately help to minimize unequal distributions of resources between men and women (e.g., gender wage gap).