We describe a food-based system for quantitatively evaluating habitat quality for deer called the Forage Resource Evaluation System for Habitat and provide its rationale and suggestions for use. The system was developed as a tool for wildlife biologists and other natural resource managers and planners interested in evaluating habitat quality and, especially, comparing two or more patches of habitat or the same patch at different seasons or under different conditions. It is based on the quantity (of biomass) and quality (digestible energy and digestible protein) of the habitat's food resources in relation to user-specified metabolic requirements of deer (which differ with species, age, sex, season, and reproductive status). It uses a linear programming algorithm to determine the suitable forage that can sustain deer at the specified requirements.