Taking an attractive approach to a study heretofore reviewed in only superficial terms, Howard Lamar and Leonard Thompson provide a fascinating and at times profound basis for comparing processes within the American and South African frontiers. Especially pertinent is their jointly authored introduction in which, after reviewing the literature, they provide a definition of a frontier as a zone of interpenetration between two previously distinct societies. Their definition is made usable in the subsequent four sets of paired essays, with each set focusing upon a broad historical process associated with the two frontiers. In the first and best pair, Robert F. Berkhofer, Jr., and Hermann Giliomee explore the processes in the development of the American and South African frontiers. Berkhofer in particular continues his work on group identities and group perceptions, which ought to be of specific interest to American historians. Giliomee's essay is a good synthesis of recent scholarship and also serves as a superb introduction to the issues in South African historiography. In the second set, Clyde Milner {II} on the United States and Christopher Saunders on South Africa deal with political processes in frontier zones and examine the roles of allies among participants. In the third set, Ramsay Cook on North America and Robert Ross on South Africa describe social and economic processes. Finally, James Axtell on North America and Richard Elphick on South Africa analyze Christianity on the frontier, though both essays also help to complement points raised in the third section of the volume. This book should foster a reconsideration of comparative strategies in historical assessment. However, frontier specialists will wonder why the contributors gave so little attention to competitive legal systems, both formal and informal, or to the land policies of the Europeans, designed to regulate as well as to permit expansion by European settlers. Less explicit, too, are the editors' criteria for determining the impact of frontier history on the metropolitan society after the frontier has closed. These criticisms are minor, however, when viewed.