Despite lacking a commonly shared definition, social mechanisms have recently received considerable attention in sociology. Social inequality research has been a trailblazer in providing examples of how social mechanism can further, theoretically and methodologically, progress. Two different understandings of social mechanisms are reflected in the literature. One refers to theoretical and methodological precision when describing the causal chains that lead from specific antecedents to specific outcomes. The other is a program designed to articulate a complete taxonomy of a limited number of mechanisms as abstract ideas to explain social inequalities. I discuss both approaches how they can fruitfully refer to each other. In the final section, I discuss social mechanisms in the view of a new challenge to social inequality research, that is, a growing interdisciplinary interest in gene–environment interference. By superseding the old and fruitless nature-versus-nurture debate, new fields of social inquiry emerge, but pose also the question what it can add to a better understanding of inequality-generating social mechanisms. As I will show, the inclusion of genetic information in social science explanations does not threaten sociology as a discipline, but will potentially enrich both the currently proposed mechanistic approaches in social inequality research.