I: Introduction; 1: Introduction; 2: Methods; II: Gender and Grade-Level Effects; 3: Gender Differences in Late Childhood and Early Adolescence *; 4: Trends Over Time and Changes in Gender Differences During Adolescence *; III: The Impact of Pubertal Timing and Physical Characteristics; 5: The Social-Psychological Effects of Puberty on White Females 1; 6: The Social-Psychological Effects of Puberty on White Males *; IV: The Impact of School Environment; 7: The Effect of Type of School Environment Upon Attitudes Toward School and Upon The Self-Image; 8: The Effects of Type of School Environment Upon Peer Relationships, Independence, Future Plans, and Conformity Behavior; 9: Individual Change and Recovery: Self-Esteem *; 10: Individual Change and Recovery: Extracurricular Participation and GPA *; V: Factors That Mitigate or Aggravate The Early Adolescent Transition; 11: Cumulation of Change *; 12: Adjustment to the Junior High School Transition: The Effect of School Properties and Individual Resources on Self-Esteem *; 13: Adjustment to the Junior High School Transition: Other Interrelationships *; VI: Conclusion; 14: Summary and Conclusion