Adaptability refers to an individual's cognitive, behavioural, and emotional adjustment in the face of novel, changing, or uncertain situations. A growing literature has demonstrated the influence of adaptability on students' academic outcomes at primary, secondary level, and more recently, tertiary levels; however, its influence on students' academic outcomes on postgraduate psychology conversion courses -- who are typically transitioning back into education and focusing on a different academic discipline -- has yet to be examined. In this study, students enrolled on a postgraduate psychology conversion course in higher education were assessed for their adaptability, academic motivation, and academic background in semester 1. Their academic achievement (grade point average) was then obtained from the Student Records System, along with demographic information at the end of semester 3 upon course completion. Bivariate (zero order) correlation analyses revealed that only adaptability and disability status were significantly associated with academic achievement. A multiple regression analysis revealed that adaptability was the strongest predictor of academic achievement. These findings have important implications for researchers and educators seeking to understand students' adjustment to university -- and postgraduate psychology conversion courses in particular -- and its influence on academic outcomes.