The United States of America needs STEM trained workers, STEM faculty and STEM professionals to improve its technical and professional workforce in order to maintain leadership in a global economy. However, American students are not opting to remain in a STEM course of study, and this is especially so for women and minorities. Of the students who pursue post-secondary education, the majority of movement away from STEM majors occurs in the first two years. Thus, educators are concerned with investigating factors that may influence students' persistence and success when in a STEM track of learning. To that end, this quasi-experimental mixed-method study was concerned with investigating the effects of participation in the design process on student self-efficacy and content knowledge gains in an undergraduate anatomy and physiology laboratory. Over fifty students participated in a design task that paralleled the topic being studied in a given semester and were given efficacy surveys along with lab practicums. Qualitative efficacy data, quantitative efficacy data and quantitative practicum results were analyzed and triangulated to produce a meta-inference as to the effect of participation in the design project had on student learning. Preliminary results indicate that the design process makes statistically significant impacts on both self-efficacy and content knowledge in the given context. The author follows with a discussion of the impact of design-based learning in the undergraduate biology classroom and implications for further research are considered.