Purpose: To investigate associations between adolescent screen time behaviors, screen time rules, and presence of electronic media in the bedrooms of adolescents. Methods: Parents and adolescents (N = 160 dyads) from the cities of Boston, Cincinnati, and San Diego were asked to complete a questionnaire which included questions related to demographics, screen time rules, availability of media devices, and screen time behavior. Separate multiple regression models were used for adolescent and parent reports to test correlates of adolescent television (TV) watching, video game play, and computer usage for entertainment. Results: Data from adolescents indicated that rules for watching TV, computer usage, and total number of screen time rules were significantly correlated with time spent watching TV (β = -.22, p < .01), playing video or computer games (β = -.18, p < .05), and using the Internet and/or computer for entertainment (β = -.18, p < .05), respectively. Data from parents indicated that TV rules were significantly associated with lower rates of TV viewing, and parent-adolescent agreement on rules strengthened this relationship. Data from parents as well as adolescents indicated that the presence of a TV in the bedroom was positively associated with TV viewing time (β = .18 and .24, p < .05, respectively). Adolescent data indicated a positive association between having at least one video game system in the bedroom and time spent playing video games (β = .19, p < .05). Conclusion: Having clear rules, setting limits on screen time, and not having screen-based media in the bedroom were associated with fewer hours of screen time for adolescents. © 2011 Society for Adolescent Health and Medicine.