Difficulties with self-regulation are implicated in the development of emotional and behavioral problems during adolescence. Although children’s ability to regulate their behaviors continues to improve throughout childhood and adolescence, it remains unclear how contextual risk factors might influence this development during the transition to adolescence, or how variation in the development of self-regulation predicts adjustment. Using a community sample of 214 8–12 year-olds (T1 M = 9.5, SD = 1.01), we examined growth trajectories of effortful control and impulsivity over three years and tested predictors and outcomes of these trajectories. Although predictors of initial levels of self-regulation were largely equivalent for both effortful control and impulsivity, contextual risk factors were related to variations in the development of impulsivity but not effortful control. However, increases in effortful control, but not impulsivity, were associated with level and rate of change in adjustment problems and positive adjustment, suggesting that different dimensions of self-regulation have different antecedents and outcomes in pre-adolescence and adolescence.