Many consider the world to be morally better today than it was in the past and expect moral improvement to continue. How do people explain what drives this change? In this paper, we identify two ways people might think about how moral progress occurs: that it is driven by human action (i.e., if people did not actively work to make the world better, moral progress would not occur) or that it is driven by an unspecified mechanism (i.e., that our world is destined to morally improve, but without specifying a role for human action). In Study 1 (N = 147), we find that those who more strongly believe that the mechanism of moral progress is human action are more likely to believe their own intervention is warranted to correct a moral setback. In Study 2 (N = 145), we find that this translates to intended action: those who more strongly believe moral progress is driven by human action report that they would donate more money to correct a moral setback. In Study 3 (N = 297), participants generate their own explanations for why moral progress occurs. We find that participants’ donation intentions are predicted by whether their explanations state that human action drives moral progress. Together, these studies suggest that beliefs about the mechanisms of moral progress have important implications for engaging in social action.