Many unions in the United States have for several years engaged in what is known as pattern bargaining a union determines a sequence for negotiations with firms within an industry where the agreement with the first firm becomes the take it or leave it offer by the union for all subsequent negotiations. In this paper, we show that pattern bargaining is preferred by a union to both simultaneous industry wide negotiations and sequential negotiations without a pattern. Allowing for interfirm productivity differentials within an industry, we show that for small differentials, the union most prefers a pattern in wages, but for a sufficiently wide differential, the union prefers a pattern in labor costs. Finally, we demonstrate that pattern bargaining can be a significant entry deterrent. This provides an explanation for why incumbent firms in an industry may support the use of pattern bargaining in labor negotiations.