In this introduction to The Handbook of State Capitalism and the Firm, we provide an overview of state capitalism, its evolution, diversity, and theoretical implications. We clarify the tension between the market and the government that drives state intervention in the economy. A brief historical overview of state capitalism provides a much-needed background to explicit and implicit discussions of the diversity of dimensions of state capitalism. We document how state capitalism seems to have followed a pendulum between periods of high dominance and periods of retrenchment that have resulted in the transformation of the literature over time. We also explain the variety of state capitalism that has been implemented across countries and time. We then outline the diversity in the theorization of state capitalism as a phenomenon and the implications of the cross-border expansion of state capitalism. We conclude with an overview of the potential avenues for future research on state capitalism and the firm.