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 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.