BackgroundPromoting uptake of evidence-based innovations in healthcare systems requires attention to how innovations are adapted to enhance their fit with a given setting. Little is known about real-world variation in how programs are delivered over time and across multiple populations and contexts, and what motivates adaptations.MethodsAs part of the BeneFIT study of mailed fecal immunochemical tests (FIT) to increase colorectal cancer screening, we interviewed 9 leaders from two participating Medicaid/Medicare health insurance plans to examine adaptations to their health plan-initiated mailed FIT outreach programs in the second year of implementation. We applied an adaptation and modification model developed by Stirman and colleagues to document content and context modifications made to the two programs.ResultsBoth health plans made substantial changes to their programs in the second year; adaptations differed substantially across health plans. In Health Plan Oregon, adaptations generally targeted health centers and member populations, most content adaptations involved tailoring program components, and the program was expanded to four additional health centers. In contrast, Health Plan Washington’s second-year content adaptations were primarily at the level of members, and generally involved adding program components. Moreover, Health Plan Washington undertook large-scale context adaptations to the setting where the program was led (local vs. national), the personnel who administered the program (vendor and staffing), and the population selected for outreach (limiting outreach to dual-eligible members).ConclusionsBoth programs implemented a variety of adaptations that reflected the values and incentives of the broader health plan contexts. Financial incentives for screening allowed Health Plan Oregon to expand but led Health Plan Washington to offer more targeted outreach to a subset of eligible enrollees. The breadth of changes made by each health system reflects the necessity of evaluating programs in context and adjusting to specific challenges as they are identified. Further research is needed to understand the effects of these types of adaptations on program efficiency and enrollee and health system outcomes.