We review the empirical accounting literature on private firms. Recent advances in data gathering provide new openings to examine private firms which, despite driving half of private sector economic activity, have historically been challenging to study. We provide a conceptual framework to organize the literature, centering on information production, information verification, and information dissemination. Four key takeaways emerge from our review. First, private firm settings offer unique advantages for understanding the economic role of accounting. Because private firms face less regulation than public firms, their accounting choices can shed light on economic tradeoffs that public firm choices cannot. Second, there is limited descriptive evidence on many fundamental accounting choices, including the extent to which private firms follow US GAAP, obtain an audit, or use various management accounting practices. Third, studies jointly modeling private and public firms provide more complete, robust analyses of the economy, regulation in particular. Fourth, private and public firms differ on many central dimensions, which raises difficulties related to conducting empirical analysis and assessing generalizability.