This chapter is devoted to discussions of how assessments of early childhood development (ECD) interventions in developing countries can be improved and extended. There are estimates that ECD problems are widespread in developing countries, increasing evidence that what happens in early childhood affects significantly options and productivities over the life cycles but very little systematic evidence to support that the impacts of these ECD programs are large or, more importantly, that the benefit-to-cost ratios of ECD interventions are high – particularly in light of the heterogeneous market, policy, and cultural contexts across developing countries that may limit the transferability of inferences from one context to another. Therefore the returns are potentially great not only for those who already are persuaded that more resources should be devoted to EDC interventions in developing countries in order that they can make their case more persuasively but also for those who are concerned more broadly about prioritizing resource allocations across what might seem to be a number of strong but difficult-to-compare alternatives ranging from other human resource investments to physical infrastructure investments to policies that affect markets such as for international goods and services and labor and capital flows, to have more systematic evaluations of the impacts of ECD interventions and of their benefit-to-cost ratios.