OBJECTIVE: Characterize key factors and training needs of U.S. cancer centers in implementing family caregiver support services. METHODS: Sequential explanatory mixed methods design consisting of: (1) a national survey of clinicians and administrators from Commission-on-Cancer-accredited cancer centers (N = 238) on factors and training needed for establishing new caregiver programs and (2) qualitative interviews with a subsample of survey respondents (N = 30) to elicit feedback on survey findings and the outline of an implementation strategy to facilitate implementation of evidence-based family caregiver support (the Caregiver Support Accelerator). Survey data was tabulated using descriptive statistics and transcribed interviews were analyzed using thematic analysis. RESULTS: Top factors for developing new caregiver programs were that the program be: consistent with the cancer centers mission and strategic plan (87%), supported by clinic leadership (86.5%) and providers and staff (85.7%), and low cost or cost effective (84.9%). Top training needs were how to: train staff to implement programs (72.3%), obtain program materials (63.0%), and evaluate program outcomes (62.6%). Only 3.8% reported that no training was needed. Qualitative interviews yielded four main themes: (1) gaining leadership, clinician, and staff buy-in and support is essential; (2) cost and clinician burden are major factors to program implementation; (3) training should help with adapting and marketing programs to local context and culture; and (4) the Accelerator strategy is comprehensive and would benefit from key organizational partnerships and policy standards. CONCLUSION: Findings will be used to inform and refine the Accelerator implementation strategy to facilitate the adoption and growth of evidence-based cancer caregiver support in U.S. cancer centers.