The main aim of this study was to gain a better understanding of why students abandon their studies, or perform less well than expected given their high school grades, and to develop predictive models that can help identify those students most at-risk at the time they enter college. This will allow teachers and those responsible for student services to better support these students with early interventions. Due to their higher risk profiles, the investigation pays particular attention to males and students with disabilities. The objectives of this study were to: (1) compare the retention profiles of the targeted groups and establish baseline data; (2) gain a better understanding of the reasons why students leave prior to completing their diploma; (3) identify characteristics that contribute to poor performance and attrition, and (4) develop models that can identify students with the highest probability of academic failure by exploring the contributions made by a combination of background, psycho-social and study skill variables and high school grades. (Contains 75 tables and 35 figures.) [Support for this research was provided by la Programme d'aide a la recherche sur l'enseignement et l'apprentissage (PAREA, Quebec), the Canadian Council on Learning (CCL) and Dawson College. Executive summary provided in French and English.]