This paper evaluates harvesting efficiency for the universe of vessels that participated in the West Coast groundfish trawl fishery two years prior to and six years following the intro- duction of an individual fishing quota (IFQ) regulation. Our economic efficiency measures control for delayed fleet restructuring and potentially confounding effects of unobserved stock abundance and/or other time-varying factors. We find that under IFQs, redundant vessel capital exited the groundfish fishery at a rate of 5.77% per year, and resource rent increased at a rate of 6.02% per year. Annual resource rent is estimated at $31.26 million in the sixth year of the IFQ regulation, with additional gains of $5.059 million per year pend- ing due to incomplete fleet rationalization. Our findings suggest that efficiency gains from reversing the economic tragedy of the commons in fisheries derive in large part from costs savings that may take years to materialize. Efficiency gains under IFQ regulations may be substantially larger than acknowledged in earlier literature.