This paper presents a model of a professional sports league and analyzes the effect of luxury taxes on competitive balance, club profits, and social welfare. It shows that a luxury tax increases aggregate salary payments in the league and produces a more balanced league. Moreover, a higher tax rate increases the profits of large-market clubs, whereas the profits of small-market clubs only increase if the tax rate is not set inadequately high. Finally, we show that social welfare increases with a luxury tax. Keywords: sports league, luxury tax, social welfare, competitive balance