Haber and Toro (2004) provide a thorough review of various theories that have been applied in recent research on homeless children and youth. The theories most relevant to homeless youth include variants based on social learning theory (Bandura, 1977; Patterson, 1982). The Risk Amplification Model (RAM), one of the most widely applied of these variants, posits that noxious early environments, including poor parenting practices in the home, put youth at risk for homelessness and that being homeless further "amplifies" the risk for poor outcomes among such youth (Paradise et al., 2001; Whitbeck & Hoyt, 1999). The RAM suggests that risk is amplified by homelessness through victimization on the streets, engagement in subsistence strategies (e.g., stealing food, prostitution), association with deviant peers and adults, and other negative experiences.
Cross-sectional studies provide some empirical support for the RAM. For example, homeless youth tend to come from more deleterious home environments and experience higher rates of victimization compared to matched housed youth (Robertson & Toro, 1999). In a more direct test of the RAM, Whitbeck, Hoyt, and Yoder (1999) found that affiliation with deviant peers, deviant subsistence strategies, risky sexual behaviors, and substance use amplified the effects of a negative family environment on victimization and depressive symptoms among homeless female youth (but not among homeless males).
There is also some support from longitudinal studies. Using the Detroit-based dataset described earlier, Lombardo and Toro (2005) found that family conflict was related to heightened self-reported symptomatology and deviant peer associations, and that both of these were associated with risky sexual behaviors and substance abuse six months later. Analyses testing the RAM over longer periods of time (up to 6.5 years) are currently being conducted by Toro and colleagues.