This presentation reports individual differences in L2 English proficiency gains after one year in an intensive English program at a small private university in Japan, using test scores, a survey, and interviews. For the current study, cluster analysis was used to identify subgroups from a large cohort based on their test preparation and experience. Cluster analysis, a multivariate exploratory procedure, revealed five subgroups, organised by their proficiency gains or losses, and test familiarity and preparation.