Within design thinking, designers are responsible for generating, testing, and refining design ideas as a means to refine the design problem and arrive at an effective solution. Thus, understanding one's individual idea generation experiences and processes can be seen as a component of professional identity for designers, which involves the integration of knowledge, action, and being in support of the professional self. Using written journal responses from graduate students in an introductory course in instructional design, this study explored how students used reflection to reconstruct experiences relating to the emergence of design ideas. Findings indicate that students were able to use reflection in support of professional identity development concerning design ideas, although attention to emotional aspects was lacking and many struggled to move from descriptive writing to meaning-making. Implications for professional identity development for designers and for future research are discussed.