Preparing engineering undergraduate students for the workforce is a goal of engineering programs. Engineering educators arguably provide students with conceptual understanding of engineering fundamentals; however, few studies focus on how knowledge of these concepts transitions into the engineering field. Concept inventories have been used in engineering disciplines as a form of student assessment of conceptual understanding. As measured by concept inventories, conceptual knowledge is presumed to be important for conceptual growth toward successful engineering practice. This study explores the performance of strength of materials conceptual understanding between engineering undergraduate students and practicing engineers. The strength of materials concept inventory was implemented, and data were collected from 153 engineering undergraduate students and 119 practicing civil engineers. The statistical analysis revealed inconsistency in performance across concepts and that structural engineers performed significantly better than nonstructural engineers and engineering undergraduates in 15 of the 23 questions. The difference in performance could be due to the way concepts are situated and applied across academic and workplace contexts.