A reference on the history of chaos theory, told by the pioneers themselves. It also provides a historical introduction to the concepts. There are eleven contributions, and six of them are published here for the first time - two by Steve Smale, three by Yoshisuke Ueda, and one each by Ralph Abraham, Edward Lorenz, Christian Mira, Floris Takens, T.Y. Li and James A. Yorke, and Otto E. Rossler.