Economists have devoted considerable effort to explaining how a market economy functions, but they have given a good deal less attention to explaining how a market economy is formed. In this book, Jean Ensminger analyzes the process by which the market was introduced into the economy of a group of Kenyan pastoralists. She employs new institutional economic analysis to assess the impact of new market institutions on production and distribution, with particular emphasis on the effect of institutions on decreasing transaction costs over time. Having compiled an extraordinary longitudinal data set that tracks a group of households over considerable time, she traces the effects of increasing commercialization on the economic well-being of individual households, rich and poor alike. In addition, employing anthropological methods, she analyzes the process by which institutions themselves are transformed as a market economy develops. Changes in labor relationships, property rights, and the transfer of political authority from the council of elders to the state are considered in particular detail . This case study points out the importance of understanding the roles of ideology and bargaining power - in addition to pure economic forces, such as changing relative prices - in shaping market institutions. The combination of new institutional economic analysis and richly detailed anthropological case study produces a work full of insights that may serve as the basis for a more adequate theory of economic development and social change.