The Interstate Commerce Commission was the first federal regulatory agency. In its 90 years of sway over American railroads, it remained ""extremely conservative,"" ""passive,"" ""permissive."" The authors, who regret that the rails were never nationalized, blame an ""entrenched staff"" for this passivity, thus rejecting both Gabriel Kolko's view that the ICC was a self-serving instrument of rail owners and Albro Martin's argument that the ICC was captured by ""railroad-hating Progressives."" This entry in the Essays in American History series tends to focus on the agency's legal mandates in discussing the perennial wrangles over rates and services. It took national crises to cut the knots and make policy, yet the main results in the Depression and both world wars were inflated rates, badly cut services, or both. The competing interest groups that shaped each ICC dispute remain shadowy, as do such elements of the economic context as the pre-WW I collapse of rail speculation. The Hoogenbooms do about as well as anyone could with the approach of taking the Commission as a subject in itself; their documentation is extensive and the book will be a standard reference.