grounded in a conceptual framework that reflects a developmental perspective. Four key features of a developmental framework are important as a basis for prevention and promotion: (1) age-related patterns of competence and disorder, (2) multiple contexts, (3) developmental tasks, and (4) interactions among biological, psychological, and social factors (Masten, Faden, et al., 2008; Cicchetti and Toth, 1992; Kellam and Rebok, 1992; Sameroff and Feise, 1990).

Understanding the age-related patterns of disorder and competence is essential for developing interventions for prevention and promotion. Healthy human development is characterized by age-related changes in cognitive, emotional, and behavioral abilities, which are sometimes described in terms of developmental milestones or accomplishment of developmental tasks (discussed in further detail below). The period from conception to about age 5 represents a particularly significant stage of development during which changes occur at a pace greater than other stages of a young person’s life and the opportunity to establish a foundation for future development is greatest (National Research Council and Institute of Medicine, 2000; see also Chapter 5). Developmental competencies established in one stage of a young person’s life course establish the foundation for future competencies as young people face new challenges and opportunities. Adolescence introduces significant new biological and social factors that affect developmental competencies, particularly related to behavioral decision making. A solid foundation of developmental competencies is essential as a young person assumes adult roles and the potential to influence the next generation of young people.

The age at which disorders appear also varies. For example, a national survey on the lifetime prevalence of mental disorders in the United States indicates that the median age of onset is earlier for anxiety disorders (age 11) and impulse control disorders¹ (age 11) than for substance use disorders (age 20) and mood disorders (age 30) (Kessler, Berglund, et al., 2005). The majority of adults report the onset of their disorder by age 24 (Kessler, Berglund, et al., 2005), and evidence suggests that initial symptoms appear 2-4 years prior to onset of a full-blown disorder (see Chapter 2). Other studies also indicate that early onset of symptoms is associated with greater risk of adult disorders, including substance abuse and conduct disorder (Kellam, Ling, et al., 1998; Gregory, Caspi, et al., 2007).