The objective of this paper is to develop insights into firms’ strategic capability development processes within product innovation projects. In particular, the research aims at investigating the interactions among product innovation, knowledge processes, and capability development within firms. Building on qualitative data from the auto-industry, our analysis reveals that across four product innovation projects, the case company developed architectural knowledge and capability. Findings reveal that, along with changes at each level of product architecture, “design knowledge” and “design capability” have been developed at the same level of product architecture, leading to capability development at that level. Furthermore, findings suggest that such capability transformation resulting from knowledge and capability creation over the course of case projects leads to modularization of product architecture. Overall, the research contributes to identifying and emphasizing the role of micro processes in capability development and renewal, which in turn enhances our understanding of strategic capability development processes.