The main purpose of this study was to examine the relationships between parental and children's physical activity and screen time behaviors in a large sample of children in the early years. The results are based on 738 children aged 0-5 years and their parents from the Kingston, Canada area. Parents completed a questionnaire from May to September 2011 that assessed sociodemographic characteristics, their physical activity and screen time, and their child's physical activity and screen time. Logistic regression models, adjusted for potential confounders, were conducted. Parents in the lowest quartile of physical activity were 2.77 (95% confidence interval (CI): 1.68-4.57) times more likely to have a child in the lowest quartile of physical activity compared with parents in the highest quartile of physical activity. Relationships were stronger in two parent homes compared with single-parent homes. Parents in the second (odds ratio = 2.27, 95% CI: 1.36-3.78), third (2.30, 1.32-3.99), and fourth (7.47, 4.53-12.33) screen time quartiles were significantly more likely to have a child in the highest quartile of screen time compared with parents in quartile one. To optimize healthy growth and development in the early years, future family-centered interventions targeting both physical activity and screen time appear important.