The development of algebraic topology in the 1950's and 1960's was deeply influenced by the work of Milnor. In this collection of papers, the reader finds those original papers and some previously unpublished works. The book is divided into four parts: Homotopy Theory, Homology and Cohomology, Manifolds, and Expository Papers. Introductions to each part provide some historical context and subsequent development. Of particular interest are the articles on classifying spaces, the Steenrod algebra, the introductory notes on foliations and the surveys of work on the Poincare conjecture. Together with the previously published volumes I-III of the ""Collected Works"" by John Milnor, volume IV provides a rich portion of the most important developments in geometry and topology from those decades. This volume is highly recommended to a broad mathematical audience, and, in particular, to young mathematicians who will certainly benefit from their acquaintance with Milnor's mode of thinking and writing.

The field of differential topology underwent a dramatic development period between 1955 and 1965. This collection of articles written by one of the creators of this field contains not only original papers, but also previously unpublished expository lectures. It includes commentary by the author, filling in some of the historical context, and outlining subsequent developments. It includes a rich bibliography of newer and older papers, providing a wider and deeper understanding of the subject. It also outlines the actual state of the art, and provides an index that will allow the reader to browse easily through the book. Of particular interest are the articles related to the existence of exotic differentiable structures on spheres, the achievement for which J. Milnor was awarded the Fields Medal in 1962.