Radical product development projects, which are undertaken to create new categories of products, present significant challenges to development teams. In such settings existing formal processes may be limited or inappropriate, and objectives may be ambiguous and changing. The generation of a novel product concept early in the process can play an important role in guiding development teams, but the process by which teams later change concepts, as may be required within radical contexts, has merited further research. This study investigated how teams change novel product concepts after initial generation, employing an inductive case-study method drawing from 51 interviews with members of six radical development projects. The empirical results found that concepts were described in terms of concept components—elemental descriptive forms that included verbal stories, verbal metaphors, and physical prototypes. When changes were required to concepts due to new technical or market information, rather than reconsider the overall concept through iteration to earlier product definition stages, teams shifted individual concept components, with a new component replacing a component of similar descriptive form. Over half of concept components observed across cases came after the initial generation of concepts in later elaboration and shifting. Contrary to expectations, development teams maintained reference not only to the revised concept but also to the deferred original concept. The case of a novel electronic book development project is used to illustrate the process, along with evidence of concept shifting across cases. The detailed findings expand our understanding of how formal processes may be augmented in radical innovation settings and how concepts are actually used by development teams in changing circumstances.