Block grants were first enacted during the Johnson administration, in 1966. Three subsequent surges in the use of block grants occurred during the Nixon, Reagan, and Clinton administrations. Experience with block grants offers several lessons. The real value of block grant funding tends to diminish over time. Once in operation, Congress gradually erodes the flexibility of block grants. Block grant implementation is smoothest when states can draw upon existing administrative capacities. This study did not find consistent evidence that states use block grants to redirect benefits away from those with the greatest need.