Applied researchers, whether working with the framework of design-based research or intervention science, face a similar implementation challenge: practitioners who enact their programs typically do so in varied, context-specific ways. Although this variability is often seen as a problem for those who privilege fidelity and standardization, we argue for the advantages of researcher-practitioner collaborations that encourage local adaptation and ingenuity. We develop this argument for adaptive interventions by discussing two design-based research projects, Critical Civic Inquiry (CCI) and Science Literacy through Science Journalism (SciJourn), which create opportunities for youth to develop civics and science literacy respectively. CCI and SciJourn aim to build curricula that will travel to new schools and districts, but not through standardization. This is a delicate combination: the program must be flexible enough to enable productive adaptation, without being so protean that practitioner's implementations lack substantive commonalities. We present two cases that show how project designers have sought to distinguish between invariant principles that define the intervention and heterogeneous practices that vary across sites. The cases also show how the model has improved when teachers can adapt it to their institutional context and when teachers and researchers establish social norms that encourage dialogic interactions.