Radio-collars equipped with activity monitors were attached to 18 black bears (Ursus americanus) in Cherokee National Forest, Tennessee. Bears exhibited a crepuscular pattern of activity that varied seasonally. Activity levels were low after bears emerged from dens, escalated rapidly in June and July, reached a peak in August, and diminished gradually until denning. Activities of bears were affected by individual differences among bears, weather factors, and denning. Sex, age, and reproductive classes also affected activity patterns. Adult male bears were the most active group, whereas females with cubs were the least active, although seasonal variation in activity patterns among different age and reproductive classes was evident. The pattern of activity for bears suggested that breeding may occur in early August.