Purpose: As sustainability teaching and learning rises in importance, an increasing number of higher education institutions (HEIs) are assessing the effectiveness of their approach to sustainability education. However, most assessments fall short in determining the impacts of curriculum plans on learning outcomes. Therefore, this study aims to assess the impact of curricula on undergraduate sustainability knowledge and assess opportunities for improving sustainability education in HEIs. Design/methodology/approach: A campus-wide survey deployed at California Polytechnic State University, San Luis Obispo, (Cal Poly) solicited data identifying students' sustainability knowledge score (SKS). The survey collected responses from undergraduate student groups enrolled in different curriculum plans under different academic settings. Findings: This study reveals that Cal Poly honors students enrolled in a structured sustainability curriculum have significantly higher SKS than general students (i.e. nonhonors students) enrolled in random sustainability courses. Further, taking at least three sustainability-related courses significantly distinguishes SKS for general students. The results also show that SKS does not significantly differ across colleges, suggesting that additional sustainability education can benefit all students. Originality/value: Findings of this study provide statistical evidence to justify institutional efforts to integrate sustainability into existing courses, with the minimum requirement of three sustainability-related courses to make an impact on SKS for the general student population. Such efforts could represent the first steps toward developing sustainability education at a HEI and improving sustainability learning outcomes.