Background: Modern engineering culture is rooted in assumptions of intellectual superiority. Scholars have demonstrated that smartness functions as an oppressive cultural practice in educational settings. However, the shared ways in which undergraduate engineering students understand what it means to be smart remain largely implicit and unexamined. Purpose/Hypothesis: We investigated the beliefs held by students about what it means to be smart and the role of smartness in their undergraduate education. Design/Method: We conducted one-on-one, semi-structured interviews with 20 students at a predominately White institution. Our team utilized open, descriptive coding to iteratively condense our data into categories, codes, and subcodes, followed by analysis to identify and characterize the participants' commonly held beliefs. Results: Students believed that being smart is working efficiently or maximizing outcomes while minimizing effort. Determining smartness as efficiency included social comparison and assumptions about effort, which introduced ambiguity into students' judgments of smartness. The resulting social hierarchy (relative positioning as smart) was commonly believed to enable or restrict access to necessary resources. Conclusions: Students' belief that smartness is an individual capacity to work more efficiently than others obfuscates the reality of smartness as a cultural practice that is baked into our systems and perpetuates inequity. Without action to reveal and disrupt smartness as a structural and oppressive practice, the status quo of inequitable participation in engineering will persist.