Veterans are more likely than the general civilian population to become homeless (Veteran homelessness: a supplemental report to the annual homeless assessment report to Congress, US Department of Housing and Urban Development and the US Department of Veterans’ Affairs, 2009). While veterans represent 8% of the US population, in 2010, 17% of the homeless were veterans. Nearly 50% of homeless veterans experience mental illness, and two-thirds meet the criteria for substance use disorders (National Survey of Homeless Veterans in 100,000 Homes Campaign Communities, 100,000 Homes, November 2011). Additionally, veterans on average spend nearly 6 years homeless, compared with 4 years for non- veterans. This chapter will summarize the mental health challenges of working with homeless veterans, as well as the initiatives that have recently been implemented to reduce homeless, prevent loss of housing, and address the risk factors associated with veteran homelessness.