This volume focuses on concepts central to the understanding of the key features of individuality which undergo significant transformations throughout the adolescent period: Personality, self, and ego. While rooted in distinct theoretical traditions, these three concepts, in combination, capture the core aspects of the formation of the individual's unique sense of self or identity, a psychosocial development fundamentally associated with adolescence. Consistent with the developmental-systems models of person-context relations at the forefront of current human development theory and research, the articles within this volume focus on the dynamic, reciprocal relations between youth and key socializing agents within their ecologies. Nevertheless, the articles represented in this volume illustrate that when attempting to understand the development of personality- and self-systems, scholars differ in the extent to which they place primary emphasis on the individual, on the context, or on the relationship between the two.

For instance, while Bandura (1989) stresses the importance of the individual's sense of self-efficacy in creating beliefs about personal agency, Harter, Stocker and Robinson (1996) examine the link between approval from others (e.g., peers and key adults) and perceived self-worth, and Kenny and colleagues (1993) study the impact of emotional attachment to parents on adolescents' self concepts and depressive symptomatology. Variations in research designs are also represented within this volume. Several articles employ longitudinal designs to study continuities and discontinuities in personality, self, and ego development. Damon and Hart (1982) focus on the transitions fromchildhood into adolescence in their examination of self-understanding from infancy through adolescence. Other articles emphasize the changes in personality and self that accompany the transition from adolescence into adulthood: Tubman, Lerner, Lerner, and von Eye (1992) examine stability and change in temperament, or behavioral style, while Block & Robins focus on consistencies and variations in self-esteem, and Waterman (1982) reviews evidence on identity development. Such longitudinal investigations give primacy to age-related changes in people. In addition, articles by Baltes and Nesselroade (1972) and Alsaker and Olweus (1992) employ cohort-longitudinal designs which enable one disentangle changes in self-understanding and personality that are associated with historical time, age, and birth cohort. The remaining articles focus on diversity in individual experiences across unique contextual conditions. Topics covered include factors related to these self systems associated with variation in ethnic and racial background (Lerner and colleagues, 1980; Luster & McAdoo, 1995; Spencer & Markstrom-Adams, 1990), gender (Galambos, Almeida, & Peterson, 1980), sexual orientation (Savin-Williams, 1995), and family structure (Hauser et al., 1991; Powers, Welsh, & Wright, 1994).

Despite the variation in emphasis on changes in the individual, the context, or person context changes over time, the articles in this volume underscore the point that multiple levels of the complex and dynamic person-context system must be examined. Only through such investigations can we further our understanding of the key aspects of individual differences in personality, self and ego development. Such understandingis critical for advancing our knowledge of when and at what levels we should intervene to promote a commitment to successful roles in adolescence and young adulthood.