OBJECTIVE Parental encouragement for healthy eating and physical activity has been found to be associated with the long-term healthy habits of adolescents, whereas parental encouragement to diet has been associated with disordered eating behaviors among adolescents. However, little is known about how parental encouragement changes as adolescents grow older (longitudinal trends), or how parental encouragement has changed over time (secular trends). This study examined 5-year longitudinal and secular trends in adolescents' report of their parents' encouragement to eat healthily, be physically active, and diet. METHODS Project Eating Among Teens surveyed a cohort of Minnesota adolescents (n = 2,516) in the years 1999 and 2004. Mixed-model regressions were used to assess changes in adolescents' reports of parental encouragement from early to middle adolescence (middle school to high school) and from middle to late adolescence (high school to post-high school), and secular changes in parental encouragement among middle adolescents between the years 1999 and 2004. RESULTS Longitudinally, there were significant decreases in parental encouragement to eat healthy food, be active, and diet between early and middle adolescence. Between middle and late adolescence, among males parental encouragement for all behaviors decreased, whereas among females parental encouragement to diet increased. Few secular changes in parental encouragement were observed between 1999 and 2004. CONCLUSIONS Given the importance of parental support for healthy eating and physical activity, efforts should be made to help parents maintain a high level of encouragement for their children's healthy behavior throughout adolescence. Parents of late adolescent females should aim to decrease the pressure on their daughters to diet during these critical developmental years.