Idea development in the early phases of the design process often involves the transformation of initial concepts into more feasible alternatives. However, this important component of design activity is often under-emphasized in design education, and tools to facilitate iteration of designs are limited. This study investigated Design Heuristics as a tool for the further development of initial concepts created by student designers. In a single session, advanced engineering students created initial concepts, and then used Design Heuristics to transform these concepts into alternative designs. The concept sets generated were analyzed, and eight types of transformations were identified, including the enhancement of aesthetics, features, functions, settings, materials, sizes, organizations, and usability. Design Heuristics supported students¿ concept development by providing specific suggestions about ways to iterate on their initial concepts. As a result, students explored alternative concepts by producing multiple transformations of their designs, and were more likely to select these transformed concepts as their most creative, unique, and favourite designs.