Background: Efforts to help cancer survivors meet recommended aerobic exercise guidelines report modest success, perhaps because many theory-based interventions focus on intention formation. Only about half of survivors intending to meet exercise guidelines translate their intentions into guideline adherence. Thus, understanding the determinants of both intention formation and translation is important. The multi-process action control (M-PAC) framework proposes that the theory of planned behavior explains intention formation but additional regulatory behaviors (planning, regulation of alternatives), and reflexive factors (sense of obligation, regret, investment) are needed to translate intentions into behavior. Purpose: To explore the determinants of aerobic exercise intention formation and translation in hematologic cancer survivors. Methods: Hematologic cancer survivors (N=606) completed surveys reporting their aerobic exercise motivation and participation. The determinants of intention formation and translation were analyzed using separate logistic regressions. Results: Overall, 71% of participants (n=428) intended to exercise, and 60% of intenders (n=256) met exercise guidelines. The independent correlates of intention formation (all ps<.01) were attitude (OR=1.9), perceived control (OR=1.6), descriptive norm (OR=1.3), injunctive norm (OR=1.3), younger age (OR=2.0), and higher education (OR=2.2). The independent correlates of intention translation (all ps<.01) were a sense of obligation/regret (OR=2.5), less interest in alternative activities (OR=1.6), financially investing in personal exercise (OR=1.6), having detailed plans (OR=1.5), attitude (OR=2.0), perceived control (OR=1.7), younger age (OR=3.0), and being female (OR=1.9). Conclusions: The results support the M-PAC framework. Interventions that target both intention formation and translation may have the largest impact on exercise participation. Controlled trials are needed to test this proposition.