["Law & Society Review, Volume 56, Issue 1, Page 78-100, March 2022. ", "\nAbstract\nThe legal profession claims a duty of public service that calls on lawyers to volunteer their time through “pro bono” work (i.e., free legal service). And increasingly law firms strongly endorse pro bono and even remunerate time that is provided to clients without charge. But what happens when pro bono is mandated by the law firm, even compensated? Is altruism undermined? Drawing on a survey of 845 lawyers, we develop an integrated theoretical model to account for how volunteering takes place in the course of legal work. The analysis reveals psychological traits, collective norms, economic exchanges, and organizational dimensions shape lawyers' pro bono work in intriguing ways with marked distinctions emerging when pro bono is remunerated by firms. Collective norms known to foster altruistic behavior appear most relevant to pro bono that is outside the job (i.e., unpaid), while organizational supports and constraints as well as economic exchange factors appear most salient to pro bono that is compensated within firms. We argue that a theory of pro bono work requires a more refined understanding of the forces promoting helping behaviors across several dimensions: whether to help, how much to help, and with or without compensation.\n"]