Nearly 800 scale samples submitted by anglers were used to investigate features of the life history of steelhead trout (Salmo gairdneri gairdneri) from the Chilliwack River, a tributary of the Fraser River near Vancouver, British Columbia. After criteria for scale reading were established, data on age, fork length, sex, month and year of capture, previous spawning history and lengths at previous ages were treated statistically. Age groups are so designated as to indicate the amount of time spent in the river and in the ocean; thus 2/3 refers to fish that were 2 years in the stream and 3 in the ocean. Age composition of adult runs of steelhead trout tended to be uniform from year to year. The four major types of life history were: fish spending 2 or 3 years in fresh water and 2 or 3 years in salt water. No correlation existed between the numbers of years spent in fresh water and in salt water. Length at maturity was determined by the number of years in salt water. There was no tendency for fish of any particular age, length, or sex to return to fresh water at any particular time of year. Sixty percent of young steelhead trout migrate to salt water in the spring months as age 2 at an average length of 16.49 centimeters. Thirty-five percent go seaward as age 3 at an average length of 19.95 centimeters. A few smolts remain in fresh water until late summer. These and other findings are related to management of steelhead trout for sport fishing.