The authors' data came from the Midwestern Homeless and Runaway Adolescent Study conducted in St. Louis, Kansas City, Wichita, Kans., Lincoln, Nebr., and Des Moines, Iowa. The study information came from interviews of 602 adolescents and 201 of their parents and caretakers from early 1995 through August 1996. The adolescent interviews took place in outreach vans, restaurants, shelters, transitional living facilities, and drop-in centers as part of regular agency outreach. The youths included 241 males and 361 females ages 12-22 years. Sixty-one percent were white. These youths typically left disorganized, dysfunctional families and experienced developmental consequences that included depression, post-traumatic stress disorder, and internalization problems and drug abuse and other externalization problems. Findings suggested the need for early and effective intervention in the most disturbed families and indicated possible interventions later in the developmental process to prevent further developmental harm. Findings also indicated the need for a national policy for runaway youth based on awareness of their stage of development. Overlooking runaways or following a social policy based on a criminal justice response will undoubtedly continue or even expedite the process of their marginalization. Tables, figures, appended tables, index, and 147 references