Objective: To assess explicit and implicit attitudes toward mental illness of undergraduate students and explore associated variables. Participants: Year 1-4 undergraduate students from a large Canadian university (n = 382). Methods: Participants completed demographics, the Opening Minds Scale for Healthcare Providers, and an Implicit Association Test. Two-tailed independent and paired-samples "t"-tests, and ANOVA were performed with significance level at p < 0.05. Results: About 67.5% self-reported having experienced a mental illness and 31.2% had been diagnosed. Lower explicit stigma was associated with females, those with a history of mental illness diagnosis, and those who have had a close relationship with someone experiencing a mental illness. Faculty of Social Sciences students had significantly lower explicit stigma scores than Faculty of Engineering students. Implicit stigma did not show significant associations with any factors. Conclusions: A high proportion of undergraduate students experience mental illness. Increased exposure and experience were associated with reduced explicit stigma.