The gap between treatment development and efficacy testing to scaled up implementations of evidence-based treatment (EBT) is an estimated 20 years, and hybrid research designs aim to reduce the gap. One was used for a multisite study in cancer control, testing coprimary aims: (a) determine the feasibility and utility of a flexible EBT implementation strategy and (b) determine the clinical effectiveness of an EBT as implemented by newly trained providers. Therapists from 15 diverse sites implemented the biobehavioral intervention (BBI) for cancer patients (N = 158) as part of standard care. For implementation, therapists determined treatment format, number of sessions, and so forth and reported session-by-session fidelity. Patients completed fidelity and outcome assessments. Results showed therapists BBI implementation was done with fidelity, for example, session "dose" (59%), core content coverage (60-70%), and others. Patient reported fidelity was favorable and comparable to the BBI efficacy trial. Effectiveness data show the primary outcome, patients' scores on the Profile of Mood States total mood disturbance, significantly improved (R² = 0.06, β = -0.24, p < .01) as did a secondary outcome, physical activity (R² = 0.02, β = 0.13, p < .05). This first use of a hybrid design in health psychology provided support for a novel strategy that allowed providers implementation flexibility. Still, the EBT was delivered with fidelity and in addition, therapists generated novel procedures to enhance setting-specific usage of BBI and its ultimate effectiveness with patients. This research is an example of translational research spanning theory and efficacy tests to dissemination and implementation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).