This chapter defines attachment theory and discusses its implications for homeless youth and programs intended to assist them. Initially, attachment theory focused attention on the importance of young children's relationships with their caregivers; more recently it has helped to understand the impact of early attachments on later relationships. Many researchers, clinicians, and theorists have expanded on the tenets of attachment theory, as first proposed by John Bowlby. The primary network available to homeless youth is the homeless population unless and until they can connect with programs that will open doors to different communities and life beyond the streets. In securely attached families, parents and children work together throughout childhood, adolescence, and into adulthood to secure a mutually satisfying relationship, that meet the needs of its members through developmental changes and the vagaries imposed by the external world.