The first study of this thesis (Chapter 2) showed that the majority of the internationally adopted children are well adjusted, although a relatively large minority of adopted children had behavior... Show moreThe first study of this thesis (Chapter 2) showed that the majority of the internationally adopted children are well adjusted, although a relatively large minority of adopted children had behavior problems of clinical significance or were referred to mental health services compared with non-adopted children. Nevertheless, adoption may often be the best solution for a child who would otherwise be raised in an institution or in other adverse environments (see also Juffer, 2002; Van IJzendoorn et al., 2005). The second and third study (Chapters 3 and 4) showed several longitudinal and concurrent influences on the behavioral and social development of adopted adolescents. The second study (Chapter 3) showed that early-onset delinquency was associated with stress hyporeactivity. The differentiation between delinquency and aggression, and between childhood-onset and adolescence-onset delinquency (Moffitt, 1993) appeared to be important for our understanding of the development of externalizing problem behaviors. The third study (Chapter 4) showed that individual development from infancy through middle childhood to adolescence was rather stable and that concurrent environmental experiences and child characteristics were essential influences on middle childhood and adolescent social development. Early parent-child relationships did not determine in final form social development in adolescence, but they provided the basis for healthy social development through the influence on earlier social development, even in the absence of genetic similarities between children and parents. Bowlby__s (1973, 1980) thesis that adaptation is always a product of both developmental history and current circumstances was supported. Show less