Understanding Modern Nigeria: ethnicity, democracy, and development by Toyin Falola Cambridge: Cambridge University Press, 2021. Pp. 672. £74.99 (hbk).

invest in pro-trade policies – particularly when members are not in direct competition with each other – so that the leaders can mobilise members if the state tries to interfere. In the absence of state threats, strong leaders use their power to extort traders and embezzle market funds. Competition between traders, as well as weak leaders, can also lead to poor private governance and poorly functioning markets. Grossman concludes that private governance works best in the shadow of the state – under enough threat of interference to motivate strong leaders to build governance institutions but not so much interference that the government crushes or takes over market institutions. The book supports the argument with a rich array of original surveys, maps, administrative data, observations, and interviews with traders in Lagos. Informal work and institutions are notoriously difficult to quantify because they exist by definition outside of regulatory agencies that collect regular data and labour statistics. Grossman addressed this challenge by building a sampling frame of markets from the Lagos Waste Management Authority, mapping out every market in the city and taking a census of , shops. Grossman then randomly selected shops from this frame and surveyed  traders in face-to-face interviews with a team of enumerators. She conducted three waves of surveys in ,  and , with  traders participating in all three waves. This trove of data gives Grossman unprecedented quantitative data on the economic and political decisions of an important group of microenterprises over time. Grossman uses these data to prove her points as well as anticipate objections and alternative explanations. She illustrates the numbers with interviews, stories and observations across the market landscape in Lagos. Grossman asserts that her account of private governance institutions in Lagos marketplaces uncovers a channel for trade and development that does not require a benevolent or efficient government or even the rule of law. Instead, she argues, all a government needs to do to spur efficient private institutions is to threaten to intervene in business people’s affairs. She convincingly demonstrates that when predatory politicians work against traders’ interests, they unintentionally trigger private policies and mobilisation that benefits traders. This book should be on the reading list of scholars working on property rights, development, governance, informality, African politics and urban politics.