The present volume on Methods and Applications of Nonlinear Dynamics arose mainly from lectures given at the First International Course on Nonlinear Dynamics, which took place in Medellin, Colombia, on 1-5 September 1986. The aims of the Course were to discuss some of the fundamental theoretical ideas of modem nonlinear dynamics and their application to selected areas of physics, and also to help the participants to bridge the gap between textbook presentations and the contemporary research literature. The lectures were intended for and delivered to a PhD-level audience composed of physicists and mathematicians. They were not primarily intended for experts, but rather for scientists interested in performing experimental or theoretical research on nonlinear dynamical phenomena occurring in real physical systems.