In response to calls for engineering programs to better prepare students for future careers, many institutions offer courses with a design component to first-year engineering students. This work proposes that traditional exam-based assessments of design concepts are inadequate, and alternative forms of assessment are needed to assess student learning in design courses. This paper investigates the self-efficacy differences between a traditional exam and a two-part practicum as a mid-semester assessment for introductory engineering students enrolled in a first-year design course. Increased self-efficacy has been linked to various positive student outcomes and increased retention of underrepresented students. The practicum consisted of an in-class team design task and an out-of-class individual reflection, while the exam was a traditional, individual written exam. All students completed a pre-assessment survey and a post-assessment survey, both of which included measures of design self-efficacy. Analysis showed that the practicum increased the design self-efficacy of students more effectively than the exam. Students who identified as women had greater gains in design self-efficacy during the practicum as compared to men. Identifying as a minority subgroup student was also trending towards being a significant predictor of change in self-efficacy for the practicum. Findings suggest that a mid-semester practicum is a successful assessment of design competencies that contributes to increased first-year engineering student self-efficacy.