This formidably detailed work, the most thorough-going sort of scholarship, relies upon exhaustive employment of primary sources and is likely to deter all but the devoted or professional students of the subject. Nevertheless it forms a worthy sequel to the author's earlier volume, The Making of the Good Neighbor Policy, winner of the Boston Prize of the Conference on Latin American History. In his survey of U. S. policy towards the three major armed conflicts occurring in Latin America during the period of 1932-1942--the Chaco War (Bolivia and Paraguay) and the Leticia (Peru and Colombia) and Maranon (Peru and Ecuador) disputes--Mr. Wood finds the constant question, in Washington, was ""a variant of the classic-- Am I my brother's keeper."" During this decade, from the slow, tortuous evolution of diplomatic formulae, emerged the unique arrangement of powers and sanctions embodied today in the Organization of American States. But U.S. policy, throughout that most enlightened era in our dealings with our hemispheric neighbors, was never simple and ever cautious; ""On the whole,"" states this authority, ""the United States took a narrow view of the range of its duties.