ABSTRACTInter-role conflict occurs when the demands of one area of an individual's life interfere with the responsibilities of another area. Although a large body of research exists on the health effects of the inter-role conflict between work and family (work-family conflict or WFC), far less exists on the inter-role conflict between work and school (work-school conflict or WSC). Given that over two-thirds of college students have outside employment while enrolled in classes, and the potentially negative effects of WSC, a further understanding of WSC is an important part of supporting student health and well-being as well as the health and well-being of the workforce. This study analyzed data from 2,055 participants drawn from a Web-based survey of four geographically and ethnically diverse educational institutions across the United States. Participants reported their current employment characteristics as well as their alcohol, marijuana, and cigarette use, depressive symptomatology, and physical health. Participants with higher WSC reported higher levels of substance use and depressive symptomatology and worse physical health. Further analyses revealed the pattern of results to be consistent with the notion that the subjective experience of conflict between work and school created an aversive psychological state, and that state impacted substance use and health.