Homelessness and health: challenges for health psychology.

Homelessness can be seen as a challenge for health psychology in research and practice on several levels: analysing the risks of becoming homeless; the living conditions of being homeless and their impact on health risks and problems; homeless youth as a specific phenomenon; health problems in the context of homelessness; service utilization and barriers and effects of interventions in the context of homelessness. With these levels, a framework is outlined for the contributions to this Special Issue. In the end, homelessness is discussed as an issue for prevention in three respects for a comprehensive approach in health psychology.