Understanding how to support student reading comprehension has long been a goal for education research. Yet no existing literature review links interactional scaffolding, defined as the responsive in-person support an expert reader offers to a novice, and reading comprehension. This review employed theories of scaffolding and reading comprehension to establish a theoretical framework, used an iterative search process to account for the terminological diversity of research on interactional scaffolding, and coded the resulting 57 studies according to their research designs and findings. Conclusions about research designs indicate that the observational studies predominate with fewer experimental, mixed methods, and correlational studies. In addition, study populations are overwhelmingly in K-5 settings. Synthesizing the studies' findings produced four themes: (a) diversity in taxonomies of scaffolding, (b) a focus on contingency, (c) ways contextual and mediational resources shape scaffolding, and (d) potential pitfalls when scaffolding does not go as planned. Suggestions for future research include addressing gaps in research designs, extending and refining existing scaffolding taxa, linking specific forms of scaffolding across contexts to reading outcomes, advancing understanding of the mediational means that underpin comprehension, and deepening knowledge of developmental trajectories for comprehension scaffolding.