In project-based learning, students engage in complex tasks to investigate real-life problems (Blumenfeld et al., 1991; Doppelt, 2003). Students have a chance to construct new knowledge through the process of integrating and applying their existing knowledge. This study took an inside look at the process of project-based learning and investigates how pre-service teachers go about completing projects in a capstone course in the insight of constructivism. The results showed that the pre-service teachers in this study sought a variety of sources to locate information, and they integrated and applied both their domain and non-domain knowledge during the process.