In at least five countries in Latin America, high level research in the field in taking place. To stimulate this development both at home and abroad, Chilean mathematicians have been promoting international meetings like the III International School of Dynamical Systems, which took place at the Universidad de Santiago de Chile-Santiago in 1990. A number of distinguished mathematicians were present at the meeting, side by side with younger people interested in the subject. Several of the participants submitted original contributions to these proceedings of the school. The topics of the papers are central to dynamics: ergodic theory, real and complex foliations, fractal dimensions, polynomial vector fields, hyperbolicity, and expansive maps. Notes on the ergodic theory of plane billiards are also included. This book will be of particular interest to researchers and graduate students working in mathematics, particularly in ordinary differential equations, bifurcation theory, and dynamical systems. Also those working in mathematical physics and physics.