Identifying causal mechanisms is an essential aspect of disparities research. Rigorous investigations of mechanisms can open the black box and clarify linkages in the causal chain, indicating how effects occur. Studies of mechanisms can also illuminate novel ways to reduce inequality when intervention at the root cause of unequal outcomes is not feasible. Still, research on mechanisms can present challenges for researchers and funders alike. In this essay, the authors summarize the necessary trade-offs and inherent tensions of research on causal mechanisms, and discuss challenges and opportunities for future studies. By explicating the complexities of disparities mechanisms research and exploring ways to address these challenges, the authors hope to help researchers propose work that is both rigorous and novel. The authors also aim to help research funders understand how best to support this work in ways that align with existing interests and resources.