University entry is a time of great change for students. The extent to which students are able to effectively navigate such change likely has an impact on their success in university. In the current study, we examined this by way of adaptability, the extent to which students' adaptability is associated with their behavioural engagement at university, and the extent to which both are associated with subsequent academic achievement. A conceptual model reflecting this pattern of predicted relations was developed and tested using structural equation modelling. First-year undergraduate students (N = 186) were surveyed for their adaptability and behavioural engagement at the beginning of their first year. Following this, students' academic achievement was obtained from university records at the end of Semester 1 and 2 of first-year university. Findings showed that adaptability was associated with greater positive behavioural engagement (persistence, planning, and task management) and lower negative behavioural engagement (disengagement and self-handicapping). Moreover, negative behavioural engagement was found to inversely predict academic achievement in Semester 1, which predicted academic achievement in Semester 2. The educational implications of the findings are discussed.