In this paper, we describe a methodology for reactively revising schedules in response to unexpected events. The approach is based on recognition of constraint conflicts in the existing schedule. Alternative scheduling actions, each offering selective advantages for conflict resolution, are available for resolving these conflicts. We present a model for action selection based on an analysis of the implications of specific schedule features with respect to the needs and opportunities available in resolving the conflicts. By matching these implications with the behavioral characteristics of different scheduling actions, it is possible to identify the most appropriate reaction in a given situation. Empirical evidence is included to validate portions of this model.