Earlier timing and faster tempo of puberty have been linked to adolescents’ poor mental health. Previous research rarely adjusted for childhood mental health, did not use physical examination to assess puberty, and excluded Latinas and Asian Americans. This study addressed these limitations. We followed 822 girls, recruited at ages 6-8, for 8 years. Breast and pubic hair development and anxiety and depressive symptoms were assessed prospectively and repeatedly. Structural equation models tested whether pubertal timing and tempo were associated with adolescent mental health symptoms and whether associations varied by ethnicity. Models were adjusted for childhood mental health symptoms, body mass index, and family income. Earlier breast development was associated with higher depressive symptoms among whites (β = -.19; p < .01) and higher anxiety symptoms among Latinas (β = -.26; p < .05), but lower depressive symptoms among Asians (β = .24, p < .05). Later pubic hair development (b = .24; p < .05) and faster pubic hair tempo (β = .26; p < .01) were associated with higher anxiety symptoms among Latinas. Faster pubic hair tempo was associated with lower depressive symptoms among Asians (β = -.34; p < .05). Tempo of breast development showed no associations. Findings confirmed that earlier breast development was associated with higher mental health symptoms for Latina and white girls but was protective among Asians. Results for pubic hair and pubertal tempo were inconsistent, requiring future examination. While targeted interventions to prevent mental health problems among early-maturing girls are critical, there is variability among who might benefit most.