There has been much recent research examining online learning in universities, but two questions seem to have been largely overlooked in this context, 1) which students voluntarily utilise Web-based learning and 2) does this use influence their academic achievement? The current study aimed to determine whether the approaches to studying, ability, age, and gender of 110 undergraduates in the 2nd year of a psychology degree predicted the extent to which they utilised online learning using Web Course Tools (WebCT) in support of a core Biological Psychology unit. Data were obtained from WebCT's student tracking system, Entwistle and Ramsden's 18 item Approaches to Studying Inventory (1983) and academic records. Multiple linear regressions, and discriminant function analysis were used to examine whether individual differences predicted WebCT use, while analysis of covariance determined whether Web use influenced academic achievement. The number of hits, length of access and use of the bulletin board was predicted by age, with older students using WebCT more. These factors were also influenced by ability and achievement orientation. The degree of participation in self-assessment was not predicted by student variables, but, of those that repeated an online quiz, improvement was more likely in those with lower achievement orientation. Only bulletin board use influenced achievement, with those posting messages outperforming those not using, or passively using bulletin boards. However, since individual differences will determine the extent to which students utilise this facility it is suggested that future research should focus on developing online learning environments that incorporate activities with both a beneficial influence on learning and appeal to a wide student population.