The rapidly growing number of people who find work via online labor platforms are not employees, nor do they necessarily fit traditional conceptualizations of independent contractors, freelancers, or the selfemployed. The ambiguous nature of their employment status and its implications for worker well-being have attracted substantial controversy, but to date most empirical research in this area has focused on the market efficiency of a single platform rather than on workers themselves and related human resource management issues. Research progress will require understanding how online labor platform work differs from other types of nonstandard employment arrangements, as well as critical differences across different labor platform firms in how work and workers are managed. This paper proposes a conceptual classification framework to facilitate research on the attitudes, experiences, and outcomes of workers who use these platforms. We explore how labor platform firms' operational choices shape how control is allocated across workers, clients, and the firm, and how they influence workers' autonomy, incentives, and degree of economic dependence on the firm. Implications for theory development, research, and managing worker-firm relations are discussed.