Miniature collar-type transmitters originally designed by W. W. Cochran , Illinois, were adapted for use on timber wolves ( Canis lupus sp. ) in east-central Ontario. Wild timber wolves were captured in steel traps, restrained with a forked stick, fitted with radio-collars and released at point of capture. Receivers were adapted for use in trucks, airplanes, and for walking in rough bush country. Maximum ranges were 3.2 km with ground and 9.6 km with aircraft receivers. A preadult female tagged in July, 1964, and a lactating adult female tagged in June, 1965, were tracked intermittently for 5.5 and 2.5 months, respectively. Tracking periods for six other animals of both sexes, ranging in age from pups to adults, varied from 2 days to 4 months. The lactating female and her associated pack regularly returned to three preferred “resting sites” for various periods during July and August. Preferred areas were well drained, semi-open, mixed conifer-hardwood stands in close proximity to swamps or beaver ponds. The preadult female ranged in an area frequented by a pack, but frequently remained independent of it. A preadult male, tagged in the same region, wandered over a slightly larger area than the female. Tagged animals were active throughout all periods of the day or night. Activity increased slightly during the early evening hours. There was a slight correlation between weather conditions and patterns of behavior and activity. Apparently, tagged individuals were quickly accepted by other members of the pack.