The author furthers research on the multiple streams framework (MSF) by testing hypotheses related to the conditional nature of politics, policy, and problems streams in affecting policy outputs from both policymaking and policy implementation. The author articulates a theoretical model of the policy process where policymaking and policy implementation are separate, but interdependent processes, and generates three hypotheses related to policymaking, policy implementation, and the interdependence of those processes. Then, the author tests hypotheses with state‐level implementation of federal environmental policy over a 20 year period. Using seemingly unrelated regression (SUR), the author makes joint estimations of policymaking and policy implementation as separate, correlated processes. Findings indicate how politics affects policymaking and policy implementation is conditional on existing policies and problems, and that these two processes are not independent from each other. Conclusions connect this MSF to the broader literature and how it may address current criticisms.