The causal evidence on microcredit impacts informs theory, practice, and debates about its effectiveness as a development tool. The six randomized evaluations in this volume use a variety of sampling, data collection, experimental design, and econometric strategies to identify the causal effects of expanded access to microcredit on borrowers and/or communities. These methods are deployed across an impressive range of locations—six countries on four continents, urban and rural areas borrower characteristics, loan characteristics, and lender characteristics. Summarizing and interpreting results across studies, we note a consistent pattern of modestly positive, but not transformative, effects. We also discuss directions for future research. Microcredit, typically defined as the provision of small loans to underserved entrepreneurs, has been both celebrated and vilified as a development tool. In its heyday, microcredit was the basis for the 2006 Nobel Peace Prize and was embraced by policymakers, donors, and funders worldwide as an effective policy tool.1 But around this time, some observers, including many of the researchers represented in this volume, pointed out that the evidentiary base for anointing microcredit was quite thin. Various theories—of poverty traps, behavioral decision making, general equilibrium effects, and/or credit market competition suggest that the impacts of expanding access to credit on poor people need not be positive, and could even be negative. More recently, these same questionable methods are often invoked to criticize microlenders for high-interest rates, serial borrowing, default crises, and other symptoms of debt traps. The six studies in this volume grew out of the debates that started in the 2000s and continue today. They generate causal evidence on the impacts of microcredit on its intended users with research designs that rely on some randomness in the allocation of credit offers by individual microlenders.