Background: Engineering programs strive to retain students and prepare them for engineering careers. Introducing group design projects into courses may help keep students interested while also improving their learning outcomes. Purpose/Hypothesis: This study measures differences in student content knowledge and intention to persist in engineering between an intervention section with group design projects and a comparison section without. We hypothesized that students in the intervention section would show an increase in both outcomes that could be demonstrated with structural equation models based on social cognitive career theory (SCCT). Design/Method: Intervention and comparison sections of a statics course were taught by the same instructor with predominately lectures. Students in the intervention section participated in three group design projects that supplemented the course content. All students took pre-tests and post-tests that assessed statics content knowledge and variables in SCCT. Data were analyzed using structural equation modeling. Results: The use of projects did not result in higher self-efficacy, outcome expectations, content knowledge, or intention to persist for students in the intervention. However, for students in the intervention section, there were strong positive relationships between self-efficacy and outcome expectations and between intention to persist and content knowledge that were not demonstrated in the comparison section. Conclusions: By using SCCT to model how students develop into engineers, we could detect the effect of introducing projects into a statics course. Connections formed by students in the intervention section between their own abilities, goals, and success in engineering demonstrate that group design projects do benefit students.