This study examined the relationship between TV viewing and three year change in BMI among a community-based sample of 176 men, 428 high-income women and 277 low-income women who were aged 20-45 years at baseline. Cross-sectionally, TV viewing was positively associated with BMI among women, but not among men. This relationship was strongest among low-income women, with only a marginal relationship among high-income women. There were no significant relationships between change in BMI and number of hours of TV viewing at baseline, average number of hours of TV viewing over the three year follow-up, or change in number of hours of TV viewing from baseline to three years. These findings suggest the link between obesity and TV viewing is complex, and that TV viewing may not be the simple marker of sedentariness we may have hoped.