An epistemic account of constitutive relevance lists the criteria by which scientists can identify the components of mechanisms in empirical practice. Three prominent claims from Craver (2007) form a promising basis for an account. First, constitutive relevance is established by means of interlevel experiments. Second, interlevel experiments are executions of interventions. Third, there is no interlevel causation between a mechanism and its components. Currently, no account on offer respects all three claims. I offer my causal situationist account of constitutive relevance that respects the claims. By situating a part of a mechanism on the causal chain between the mechanism’s input and output, components can be identified with interventions...