Background: Little is known about physical activity (PA) and sedentary behavior patterning or its impact on long-term PA sustainability, particularly during the critical transition from adolescence to adulthood. Methods: Nationally representative self-reported data were collected (National Longitudinal Study of Adolescent Health: Wave I, 1994-1995; Wave II, 1996; Wave III, 2001-2002). Cluster analyses identified homogeneous groups of adolescents with similar PA and sedentary behaviors. Logistic regression predicted odds of meeting national activity recommendations in adolescence and young adulthood. Results: Seven clusters were characterized as follows: C1, high television (TV)/video, video gaming; C2, high skating, video gaming; C3, high sports participation with parents, high overall sports participation; C4, use of neighborhood recreation centers, high sports participation; C5, TV viewing limited by parents, moderate participation in school physical education (PE); C6, low parental TV control, reporting few activities overall; C7, active in school (team/individual sports, academic clubs, and PE). Odds of adolescents meeting PA recommendations were highest in C2 (odds ratio=13.1), C3 (5.8), C4 (4.2), and C7 (4.3) compared to C1. Independent of adolescent PA, absolute odds of meeting recommendations as young adults declined but were still relatively high in these clusters, indicating greater long-term PA sustainability. By young adulthood, however, overall PA declined dramatically in skaters/gamers (C2) and was notably low among those with TV viewing limited by parents (C5). Conclusions: While odds of meeting PA guidelines in adulthood declined in all clusters, the magnitude of this decline varied by cluster (declining most dramatically in skaters/gamers), providing insights into where to target effective intervention strategies that promote sustainable PA behaviors.