Although much research exists on scaffolding in reading instruction, confusion about the construct persists. In this commentary inspired by a recent article in "Reading Research Quarterly," we argue for the importance of contingency--that is, responsiveness to student thinking--in reading comprehension scaffolding. We begin by defining two sometimes nebulous constructs: scaffolding and comprehension. We then argue that the dynamic, contextual, and affective nature of comprehension calls for a focus on contingency in scaffolding interactions because the requisite assumptions of preplanned scaffolding can obscure students' emergent comprehension. To focus on contingency, three implications for research follow. First, research designs could separate interactional scaffolding from planned scaffolding so as to directly investigate the construct. Second, collaboratively analyzing video data of scaffolding interactions is an effective tool for teacher educators and researchers. Finally, researchers should consider refining, building on, or comparing their findings with existing frameworks to illuminate both the transferable and the idiosyncratic dimensions of contingent scaffolding. This could also include studying students' discursive moves in addition to teachers' utterances, which might offer a new lens on how teachers adjust scaffolds in moment-to-moment interactions. These implications lay a foundation for a research agenda that goes beyond assumptions about students built into planned scaffolding and tackles the challenges of contingent comprehension scaffolding.