Erickson provides a theory of human growth and development in terms of psychological and social stages. Erickson's theory is a "step" theory, where each stage is consecutively entered, a psychological crisis is encountered and must be resolved successfully to ensure success in future stages. ADHD tends to be a lifelong struggle and therefore affects all stages. For the purposes of this site, we will discuss the stages of Middle Childhhood (ages 6-12) and Early Adolescence (12-18), in terms of peer rejection and social difficulties (APA, 2000; Guevremont & Dumas, 1994). For a more in-depth discussion of Erickson's theory see this discussion of the Psychosocial Stages.