Book excerpt: Social experimentation randomly assigns individuals or groups to coverage by the policy of interest or a control group and then the groups are compared in terms of outcome. Greenberg (economics, U. of Maryland), Linksz (mathematics, science, and engineering, Community College of Baltimore County), and Mandell (policy sciences, U. of Maryland) seek to assess whether the substantial investment in social experimentation in the United States has resulted in significant public policy changes. After explaining the general concepts behind social experimentation, they analyze five case studies and determine that they are not of decisive importance in state policy making, but they often serve useful purposes of policy formation. Annotation (c)2003 Book News, Inc., Portland, OR (booknews.com).