Public service-motivated individuals have a greater concern for the delivery of public services and for the societal consequence of collective inaction, seeing themselves play a pivotal role in upholding public goods. Such self-efficacy and perceived importance of public service jointly motivate individuals to commit to sacrificing for the common good. Using an incentivized laboratory experiment with 126 undergraduate and graduate students at a university in the Netherlands, we explore the association between self-reported Public Service Motivation (PSM) and voluntary self-sacrifice under different task characteristics and social contexts in a Volunteer’s Dilemma game. We find that risk-taking and intergroup competition negatively moderate the positive effect of PSM on volunteering. The risky situation may reduce an individual’s self-efficacy in making meaningful sacrifice, and intergroup competition may divert attention away from the concern for society at large to the outcome of the competition, compromising the positive effect of PSM on the likelihood to self-sacrifice for the common good.