The relative nature of pubertal timing has received little attention in research linking early pubertal development with psychological adjustment. The current study examines the dynamic association between pubertal timing and internalizing symptoms among an urban, ethnically diverse sample of girls (n = 1,167; 50% Latina, 30% Black/African American, 11% Asian, 9% White). By relying on six waves of data, we detected substantial "within-person" variability in pubertal timing, which in turn related to fluctuations in depressive symptoms, global self-worth, and social anxiety in multilevel analyses. Within-person changes in the direction of more advanced development compared to peers consistently predicted more depressive symptoms; however, more advanced development was related to lower self-worth only at the beginning of middle school. By the end of middle school, less advanced development predicted social anxiety. Results challenge the notion that pubertal timing is a stable individual characteristic, with implications for studying the psychosocial correlates of pubertal development across multiple years.