The Canadian Academic English Language (CAEL) assessment is a proficiency test for university admission. Most research has focused on the paper edition, not the recent computer edition (CE). Validity research on other proficiency tests found that relationships between proficiency scores and academic achievement measures can be tenuous because other factors intervene in students' chances of success. Research on academic success has examined academic acculturation as one factor. However, the impact of acculturation on academic achievement has not been examined alongside language proficiency test scores. The current study investigated this issue by focusing on students with a range of CAEL scores and examining the relationship between CAEL-CE scores, academic achievement, and academic acculturation. Forty-four students at a Canadian English-medium university participated in the study. Students' grade point averages were obtained, and an academic acculturation questionnaire was administered. A subset of participants took part in focus groups. The findings and their implications are discussed.