This paper applies the social custom model developed by Akerlof [1980] to the problem of explaining the logic of collective strike action. The paper demonstrates the possibility of stable long-run equilibrium levels of support for a strike. We also show that the model can be applied to the issue of explaining the existence of a trade union, and builds on the results of Booth [1985] in explaining stable intermediate equilibrium membership. The paper does not claim to provide a general theory of strikes, but demonstrates the value of the social custom approach in enhancing the understanding of this class of labor market behavior.