Which sector matters most for growth and poverty reduction? For decades, many believed that agriculture's role in moving people out of poverty was peripheral, and the focus should be elsewhere (manufacturing-led growth, for instance). But, the evidence from recent empirical work is unanimous: agricultural growth has been more poverty-reducing than growth in other sectors. The continuing relevance of agriculture to economic development and poverty reduction is the centrepiece of John Mellor's insightful new book Agricultural Development and Economic Transformation. The book draws upon Mellor's own half a century of ideas and research. The central theme of the book is: ‘If the objective of a country is to reduce poverty, the most effective strategy is to promote small commercial farming'. Since the majority of rural populations is engaged in small farming activities, policies that promote commercial farming innovations amongst this population can have a larger impact on poverty reduction than those strategies that target large farms. Agricultural growth further feeds directly into food security and the nutritional needs of rural households. In Chapter 11, Mellor argues, citing the case of Ethiopia that greater agricultural output leads to greater consumption levels. An increase in food production can also directly reduce intra-household gaps in dietary intake. As households achieve greater access to food, women tend to receive and increased share of the produce. The eighth chapter of the book considers the role that governments play in facilitating agriculture-led economic growth. For example, the current Indian government has promised to double farm incomes over the next six year period. To deliver on this promise, Mellor argues, the Government needs to dedicat a share of public funds to small-farm agriculture. Mellor cites the African Union's 10 per cent of government expenditure as a reasonable target. But, this strategy additionally requires a number of functioning local-level governance structures which are broken in many developing countries. In India, agricultural extension services – a critical component of Mellor's recommendation – are conspicuous by their absence. Even the largely independent Panchayat system (the local village-level government) in India receives very little funds for promoting technological changes in agriculture. The ninth chapter describes the pre-requisites for agricultural market development: roads, and electricity. There is now a sizeable literature which points out that rapid improvement in physical infrastructure alongside policy reforms can lead to reduction in rural poverty. The key here is, the complementarity between road-building and agricultural reforms. In the absence of any reform, diversification of farm production will reap few rewards. India, which undertook a large rural road connectivity program in the 2000s, is one such case. While a large fraction of villages in India are connected by all-weather roads, agricultural incomes have stagnated. While electrification and road infrastructure are known to have a positive impact on agriculture, the effect of ICT infrastructure on small-farm agriculture remains understudied. Expansion of mobile phone coverage in rural areas in developing countries has the potential to substantially reduce informational gaps and can complement agricultural extension services. The section on the role of mobile phone, beyond its capacity to improve agricultural marketing, in the chapter is perhaps smaller than it should be. There is also a need to understand the distributional gains from access to mobile phones. Typically, local traders and large farmers enjoy greater returns to mobile phone coverage compared to small farmers. Agriculture-led economic growth can also accelerate educational attainment and access to health services, according to the tenth chapter of the book. This is, by far, the least convincing argument of the book. It is necessary to have quality publically funded education and health care in villages alongside improvements in physical infrastructure discussed in the previous chapter of the book. Public expenditure on health and education in many developing countries including India remains exceptionally low. Mellor overlooks this fact, and under emphasises the important role of public spending in these two sectors. The subsequent chapter discusses the role of agricultural price policy. Mellor argues, rightly that policy makers in developing countries should abandon inefficient fertilizer subsidies and cereal price subsidies. Similarly, debt waivers to farmers are pernicious working against agriculture-led economic growth. But this chapter overlooks the political economy of agricultural price policy. The fundamental reason why governments in developing countries pursue short-termism: large debt waivers; and higher minimum support prices – is because of the immediate gains from such policies. For instance, large debt waivers can be strategically used to influence rural voters during an election year. Chapters 12, 13 and 14 discuss various pre-requisites for agricultural development ranging from inputs to finances for small-farm agriculture. Mellor makes the case for a dedicated financial system for small commercial farmers in developing countries that is not run by the government. While theoretically valid, there are difficulties with this strategy. Sometimes, these agents or banking correspondents wield disproportionate power in disbursement of credit, and therefore, this model might, just like the traditional banking system in the rural developing world, run the risk of abuse of power. The penultimate chapter takes the issue of interaction between the rural and the urban, but the argument presented here does not distinguish between different forms of urbanisation and their impact on agriculture. In the Indian context, small towns matter more for rural India than large cities. The secondary towns are considered to have stronger linkages with the rural agrarian economy at early stages of economic development making them ideal engines for structural transformation. The concluding chapter makes the case that foreign aid does little to help small-farm agriculture. Drawing from different papers, it appears that the case for aid-effectiveness in spurring agricultural growth is weak, but Mellor also reiterates that foreign aid has an important role in building research infrastructure in the developing world. Overall the book offers a detailed roadmap for government-driven structural transformation via small-farm agriculture. The prose in the book is remarkably accessible to practitioners, students, and applied economists. However, there are gaps: the political economy of agriculture is missing from Mellor's large canvas, and the treatment of gender-dynamics in agriculture is underwhelming. Having said that, the sheer amount of detail Mellor offers from agricultural development in different developing countries is an achievement, and the book makes for an engaging read.