Drawing on niche theory, I describe the resource dimensions that compose teachers unions' niche and explain how aspects of the current political landscape buttress or undermine teachers unions' realization of those resources. I also discuss teachers unions' strategies to oppose any threats that undermine the realization of the resource arrays that make up their niche and contend that by not only resisting reforms, but also by adapting to some initiatives and collaborating with reformers to reshape other reforms, teachers unions, in all likelihood, will continue to be a powerful force in the politics of education. (Contains 1 table.)