A symposium entitled, The Ecology of Human-Machine Systems, was held at the Fifth International Conference on Event Perception and Action. This symposium examined the challenges that human-machine systems hold for an ecological approach to perception, cognition, and action and the promises that an ecological approach holds for problems that traditionally have been the domain of human factors psychology. The presenters from this symposium have been invited to submit articles about an applied ecological psychology to Ecological Psychology. Articles that are accepted for publication will be appearing in future issues of this journal. It is hoped that these articles will stimulate productive interaction between ecological and human factors psychology. This correspondence reflects the natural affinity between ecological and human factors psychology. It examines some of the issues that distinguish basic and applied research. It also considers the contribution that ecological physics can make for improving traditional approaches to task analysis. Finally, this article speculates about emerging areas of research in which the ecological approach may contribute to the design of human-machine systems.