We describe concepts, rationale, and analytical procedures for characterizing physical habitat in wadeable streams based on raw data generated from methods similar or equal to those of Kaufmann and Robison (in PB99-139156). We provide guidance for calculating measures or indices of stream size and gradient, sinuosity, substrate size and stability, habitat complexity and cover, woody debris size and abundance, residual pool dimensions and frequency, riparian vegetation cover and structure, anthropogenic disturbances, and channel-riparian interaction. We evaluated sampling precision of field habitat survey methods employed by EMAP in several hundred streams in Oregon and the Mid-Atlantic region, comparing variance among streams ('signals') with variance between repeat stream visits (measurement 'noise'). The final measure of the utility of a habitat approach is whether it is useful for interpreting controls on biota or impacts of human activity.