Youth homelessness is a growing concern in the United States. Despite difficulties studying this population due to inconsistent definitions of what it means to be a youth and homeless, the current body of research indicates that abuse, family breakdown, and disruptive family relationships are common contributing factors to youth homelessness. Moreover, the experience of homelessness appears to have numerous adverse implications and to affect neurocognitive development and academics, as well as mental and physical health. Substance use, sexually transmitted infections, and psychiatric disorders are particularly prevalent in this population. Whereas some of these problems may be short-lived, the chronic stress and deprivation associated with homelessness may have long-term effects on development and functioning. Further, difficulties accessing adequate and developmentally-appropriate health care contribute to more serious health concerns. Suggestions for future research and interventions are discussed.