There is renewed focus on the means by which workers organize against extreme economic inequality and autocracy at work. Social movement organizations, first on their own and, more recently, in collaboration with labor unions, have originated creative sectoral bargaining strategies matched with workplace activism and direct action tactics. These organizations, called "worker centers" by activists, scholars, and funders, remain largely outside of the literatures on law and social movements, labor law, and non-profit law. These formations' increasing salience in civil society invites empirical study of whether or how they promote worker voice and autonomy. This paper reports findings of a preliminary foray into such a study. Based on in-depth, semi-structured interviews with a mix of lawyers, executive directors, and organizers deeply involved in a variety of worker centers nationwide, we find these organizations are pluralistic in terms of their commitment to, and modes of incorporating, worker voice and worker leadership. We note variations among the organizations correlated with a range of factors, including racial, gender, lingual, and legal status characteristics of workers and organizational leadership. We find a major commonality among all organizations studied: worker centers pursue internal democracy because leadership deems it both instrumentally and intrinsically beneficial to the cause of improving working conditions and creating a more equitable political economy. We further examine implications of worker center governance models with regard to continuities and discontinuities with labor unions, in shaping organizational democracy and advocacy tactics, in confronting the "iron law of oligarchy," with regard to scalability, as affecting social and political democracy beyond the organization, and in relation to legal regulation and funding models.