From Andrew B. Wilson's "Five Myths About the Great Depression":
Far from a free-market idealist, Hoover was an ardent believer in government intervention to support incomes and employment. This is critical to understanding the origins of the Great Depression. Franklin Roosevelt didn't reverse course upon moving into the White House in 1933; he went further down the path that Hoover had blazed over the previous four years. That was the path to disaster. Hoover, a one-time business whiz and a would-be all-purpose social problem-solver in the Lee Iacocca mold, was a bowling ball looking for pins to scatter. He was a government activist fixated on the idea of running the country as an energetic CEO might run a giant corporation. It was Hoover, not Roosevelt, who initiated the practice of piling up big deficits to support huge public-works projects. After declining or holding steady through most of the 1920s, federal spending soared between 1929 and 1932 - increasing by more than 50 percent, the biggest increase in federal spending ever recorded during peacetime.
Read the whole thing, as they say. For further reading on the Depression, try Amity Shlaes's The Forgotten Man and Milton Friedman and Anna J. Schwartz's Monetary History of the United States, 1867-1960.