Supplementation, as used here, is planting of all life stages of hatchery-reared fish to increase natural production of anadromous salmon and steelhead trout. Through the Salmonid Enhancement Program (SEP), Canada has been experimenting with supplementation techniques at a number of British Columbia hatcheries for the past fifteen years. The original objective of this report was to ascertain the success of supplementation efforts at four British Columbia hatcheries as measured by the program goals of increased harvest; and enhancement, preservation, and rehabilitation of natural stocks in a cost-effective manner. This objective was not attainable because, while these four hatcheries have been experimenting with various spawning, rearing, and release strategies, they have never monitored natural stock survival or escapement - a situation common to other Canadian supplementation hatcheries as well. Thus while the hatcheries direct operating costs to produce a hatchery-reared chinook surviving to catch and escapement have been estimated ($380 at Quesnel Hatchery, $47 at Snoolti Creek, $85 at Spius Creek, and $45 at Kitimat) the effects of supplementation on the natural stocks, and hence the full costs or benefits of these hatcheries and of the program as a whole, are unknown. From the Canadian experience to date, therefore, one is not able to determine whether supplementation is an effective way to enhance natural stocks.