This study examines 239 cases of public participation in the United States over 30 years. It evaluates each case against five social goals: 1) incorporating public values into decisions; 2) increasing the substantial quality of decisions; 3) resolving conflict among competing interests; 4) buliding trust in institutions; and 5) educating and informing the public. The study found that in 68 percent of the cases public input improved the quality of decisions.