The cost of housing is beyond the means of a growing number of housholds. This "affordability gap" is the underlying cause of homelessness. Housing assistance to low income families is therefore a logical solution to the problem, in combination with other responses.
Dolbeare, Cushing N.
"Homelessness and the Low Income Housing Crisis,"
The Journal of Sociology & Social Welfare: Vol. 19
, Article 10.
Available at: http://scholarworks.wmich.edu/jssw/vol19/iss4/10