Wisconsin's populations of muskellunge Esox masquinongy provide an important recreational fishery. Our objectives were to (1) evaluate progress of the Wisconsin Department of Natural Resources muskellunge management plan, (2) examine subsequent changes in the fishery, and (3) evaluate Wisconsin's muskellunge waters classification system. With the goal of maintaining viable populations and a trophy fishery, the 1979 plan endorsed more restrictive harvest regulations, an increased supply of muskellunge fishing opportunities, and increased data collection. Since the 1980s, muskellunge fishing opportunities have increased 75% in terms of lake acres and 51% in terms of stream miles. Hatchery production and stocking efficacy have improved to the point where the department needs to reevaluate current stocking practices. With the establishment of a shorter season, a higher statewide minimum length limit, and an increased use of special regulations, harvest regulations have become progressively more restrictive. Concurrently, muskellunge-specific fishing effort increased from the 1980s to the 1990s. Harvest of muskellunge declined even though catch remained unchanged. Reducing the season length and increasing the overall availability of muskellunge angling opportunities did not reduce fishing effort on premier muskellunge lakes, but rather compressed effort into a shorter time period on increasingly popular waters. The reduction in harvest was associated with more restrictive regulations and voluntary changes in angler behavior (i.e., increased release of legal-sized muskellunge). Without voluntary release, it is likely that angler harvest would have exceeded levels needed to sustain the fishery. The muskellunge waters classification system, based originally on professional judgment, proved useful in distinguishing the fishery potential of lakes. Preliminary evidence suggests that voluntary constraints on harvest have not improved the size-structure of Wisconsin muskellunge populations because of continued harvest of nontrophy-sized fish. If our goal remains to provide a trophy fishery, more restrictive size-specific restrictions on harvest may be needed.