Chapter 5: Links to Underlying Brain Development -- 5.1 Activity and Related Brain Development -- 5.2 Cognition and Related Brain Development -- 5.3 Emotion, Risk-taking, Impulsiveness, and Related Brain Development -- 5.4 Mental Disorders that Arise in Adolescence -- Chapter 6: Putting it All in Context -- 6.1 Implications for Health and Social Policy -- 6.2 Implications for Education Policy -- 6.3 Promoting Adolescent Development in the Community -- 6.4 Concluding Remarks -- References -- Author Biographies