Macroeconomic development remains an important policy goal because of its ability to lift entire populations out of poverty. In our review of the literature, we emphasize that the best way to achieve this objective is to embrace a synthesis of methods and ideas, with the science of experiments as a unifying feature. Randomized controlled trials need representative data and structural modeling, and macro models need to be designed and disciplined to the realities and data of developing-country economies. Macroeconomic models have key lessons for gathering and analyzing micro evidence and for moving to an evaluation of macro policy. Resource constraints, heterogeneity, general equilibrium effects, obstacles to trade, dynamics, and returns to scale can all play key roles. A synthesis for macro development is well under way.

We propose a model with local spatial markets and heterogeneous agents to understand and evaluate the geographic expansion of bank branches after banking deregulation in Thailand. The model features heterogeneity in financial frictions across regions, with the costs of accessing credit and deposits depending on the distance from the nearest branch. Disciplined by micro estimates of the effects of branch openings, the model reproduces salient regional and aggregate patterns concerning occupational choice, financial access, and inequality. We apply the model to study two counterfactual financial sector policies in distant markets, one subsidizing branches and the other subsidizing household deposits.