Although a number of studies are devoted to studying design practice, very little is known about how the managerial decisions are made to steer the design process. This article sets forth an exploration of managerial decision making in the interdisciplinary design process. To this end, the paper derives a theoretical framework, which posits that process-level design management is based on decision-making frames that set the context for design activity. The paper provides evidence for the theoretical framework by using data from an interpretive case study of a large-scale engineering infrastructure project. The case study findings set out the role of process-level design management as the identification, enforcement, and anticipation of decision-making frames. The theoretical relevance of the findings is in the model of process-level design management described as a reflective practice. The findings contribute to practice by introducing the considerations of frame identification, enforcement, and anticipation into the design management skill set.