THANKS, W:

For three decades, we have debated what causes homelessness and how to deal with it. Is homelessness a mental health problem? A substance abuse problem? A problem caused by gentrification and urban redevelopment? Or something else again?

The Bush administration substituted a much simpler idea -- an idea that happened to work. Whatever the cause of homelessness, the solution is ... a home.

In 2002, Bush appointed a new national homeless policy czar, Philip Mangano. A former music agent imbued with the religious philosophy of St. Francis of Assisi, Mangano was seized by an idea pioneered by New York University psychiatrist Sam Tsemberis: "housing first."

The "housing first" concept urges authorities to concentrate resources on the hardest cases -- to move them into housing immediately -- and only to worry about the other problems of the homeless after they first have a roof over their heads. A 2004 profile in The Atlantic nicely summarized Tsemberis' ideas: "Offer them (the homeless) the apartment first, he believes, and you don't need to spend years, and service dollars, winning their trust."

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