Abstract
<title>Abstract</title> <p>Background. Early relational health (ERH) interventions show strong evidence for improving caregiver-child interaction and child outcomes but extending them beyond their original delivery setting to the diverse populations, settings, and countries where families are reached requires adaptation methodologies that can handle multi-component change. Existing tools such as Plan-Do-Study-Act (PDSA), the Framework for Reporting Adaptations and Modifications-Enhanced (FRAME), and human-centered design (HCD) each address part of the adaptation challenge, but none alone is sufficient for coordinating rigorous adaptation across diverse settings, populations, and countries. Methods. We describe the bundled adaptation methodology developed within the PlayReadVIP National Center, which articulates HCD, rapid-cycle iterative testing (when the field window permits it), and FRAME documentation around a functional fidelity anchor specified before adaptation begins, distinguishing the functions that must be preserved from the forms that may vary. The methodology operates through three modalities calibrated to the field window: pre-specified bundling for single-phase windows, and, where the window permits iteration, iterative bundling when needs assessment precedes the cycles and integrated bundling when it runs concurrently. Results. Three adaptations illustrate the methodology: BrincarLerVIP em Sala (Brazilian public preschools; pre-specified bundling with social-validity iteration; two arms; single 12-week term); PlayReadVIP in Bronx family childcare (FCC; iterative bundling; 16-week window; 3 PDSA cycles; n = 13 caregivers across 10 FCC homes; 30 visits); and the Connect and Play, Bond and Read Aloud (CAPYBARA) Project in Singapore (integrated bundling; needs assessment concurrent with 3 PDSA cycles; 30 coaching visits; 40 caregivers). Two further applications (rural U.S.; children with autism) are in progress. Functional fidelity was preserved and adaptation completed within available field windows in every case. In the FCC case, single-modification-per-cycle PDSA would have required an estimated 7–10 times longer; bundling allowed adaptation to fit the window the partnership afforded. Conclusions. Bundled adaptation is distinct from and complementary to existing single-framework approaches. Its functional-fidelity anchor prevents collective drift when multiple modifications are tested together, and its modality-dependent structure accommodates diverse field-window constraints. The methodology offers operational tools for coordinating adaptation across diverse settings, populations, and countries. It contributes to the emerging conversation on the pace of adaptation in implementation science.</p>