The British Columbia halibut fishery provides a natural experiment of the effects for "privatizing the commons." This study indicates that (1) the short-run efficiency gains from privatization may take several years to materialize and can be compromised by restrictions on transferability, duration, and divisibility of the property right; (2) substantial long-run gains in efficiency can be jeopardized by preexisting regulations and the bundling of the property right to the capital stock; and (3) the gains from privatization are not just in terms of cost efficiency but include important benefits in revenue and product form.