The authors propose a new means by which nonprofits can induce donors to give today and commit to giving in the future: contingent match incentives, in which matching is made contingent on the percentage of others who give (e.g., "if X% of others give, we will match all donations"). A field experiment shows that a 75% contingent match (such that matches "kick in" only if 75% of others donate) is most effective in increasing commitment to recurring donations. An online experiment reveals that the 75% contingent match drives commitment to recurring donations because it simultaneously provides social proof while offering a low enough target to remain plausible that the match will occur. A final online experiment demonstrates that the effectiveness of the 75% contingent match extends to one-time donations. The authors discuss the practical and theoretical implications of contingent matches for managers and academics.