According to the World Health Organization, six out of the top seven risk factors for chronic illness are associated with a lack of physical activity, smoking and unhealthy eating habits. Adolescence is a critical period for establishing attitudes and behaviours associated with physical activity, eating, and tobacco use, yet little is known about the relationships among the health behaviours and the reasons for initiating or avoiding them. As a result, understanding and targeting adolescent behaviour can potentially have an important impact on health status across the lifespan. Catherine Sabiston is studying what influences adolescents’ decisions to engage in healthy or unhealthy behaviours. She is reviewing several social, cultural and individual factors—such as social support and relationships, gender-stereotypes, socioeconomic status, self-perceptions, competencies and values—that affect physical activity, eating and tobacco use. Catherine is also interested in how these factors affect boys and girls differently, and whether these factors influence adolescents of a variety of ethnic backgrounds differently. This research should help explain the onset of and relationships among multiple health behaviours. Catherine will use this information to develop a school-based intervention program to target health behaviour change in adolescents, with the goal of developing realistic recommendations towards improving the long-term health status of Canadians.