Daily ranging behavior (DRB) of red colobus monkeys (Colobus badius tephrosceles) is examined to determine (1) what social and environmental variables are related to ranging patterns, and (2) how these variables are related to one another and to DRB. It is suggested that foraging constraints primarily determine variation in DRB but that other variables, i.e. rainfall and intra- and intergroup conflicts periodically influence DRB as well.