Background: Testing evidence-based interventions (EBIs) outside of their home country has become increasingly commonplace. There is a need for theoretically guided research on how to best create and test the effects of culturally adapted interventions. Objective: To illustrate how the field might raise the scientific and practical value of future effectiveness and dissemination trials of culturally adapted interventions, as well as to provide support for theoretically informed research on this subject to take greater root. Methods: Nine theories that offer guidance on how to adapt existing EBIs for a new cultural group were summarized and evaluated. Results: Commonalities among the selected theories included a focus on the need for collaboration as part of the adaptation process and shared emphasis on taking systematic steps to select an intervention to adapt, as well as calls for adaptations to be guided by specific types of empirical studies. Among the theories, variability existed in terms of what constituted an adaptation. Conclusions: As EBIs go global, intervention adaptation promises to be the subject of substantial future scholarly attention. There is a need to develop systematic evidence-based methods that allow for some degree of adaptation, while still bringing about EBIs' desired benefits.