The objective of this study was to identify parental, childhood, demographic, and social function factors associated with social network size and complexity among substance abusers using retrospective data regarding family and childhood history and current data regarding demographic characteristics and psychosocial function. The authors interviewed 505 voluntary patients with substance abuse at two university medical centers in Minnesota and Oklahoma with alcohol-drug programs located within departments of psychiatry. Data collection instruments included a childhood questionnaire, a demographic checklist, and two psychiatric rating scales of psychosocial function. The authors found that years of education, current residence with others, being actively occupied at work or school, and higher psychosocial function on two psychiatristrated scales were associated with increased social network size and complexity. Loss of mother, out-of-home placement, and runaway before age 18 were associated with smaller social networks in adulthood. Age, gender, and current marital status were not associated with social network. Regression analysis indicated that network size (i.e., the number of individuals in the network) was associated with higher psychosocial function over the last year but not over the last two weeks, whereas network complexity (ie, the number of subgroups in the network) was related to psychosocial function over both the last year and the last two weeks. These data indicate that in addicted persons, both childhood factors and current social factors affect network size and complexity. Network complexity may be amenable to short-term change, whereas network size may be more related to longer-term coping.