Byline: Asif Efrat, David Leblang, Steven Liao, Sonal S. Pandya This article analyzes the determinants of international child adoption. We argue that prospective parents' desire to reduce transaction costs and ensure a successfully completed adoption influences adoption flows. Drawing on dyadic panel data over the period 1991-2010, we fit hurdle models to identify sending-country and dyad characteristics that correlate with adoption flows. We show that an international agreement designed to ensure the integrity of adoption depresses foreign adoptions by raising transaction costs. By contrast, adoption is more likely when sending countries have a high-quality regulatory environment and when colonial or migration ties exist within the dyad. Our findings highlight the impact of transaction costs on transnational, non-market exchange, expand political economy models of migration, and emphasize the importance of private international law in international relations. Article Note: We thank the editors of ISQ and three anonymous reviewers for their helpful comments. This study has benefited from funding provided by the European Union's Seventh Framework Programme. Peter Selman assisted with the collection of international-adoption data. Katherine Holcomb and Jacalyn Huband assisted with the parallel implementation of multiple imputation on the University of Virginia's cluster. Replication materials are available at http://thedata.harvard.edu/dvn/dv/sliao. A web application to visualize dyadic international adoptions is available at https://stevenliao.shinyapps.io/Vis_adoption/. CAPTION(S): Appendix A. Adoption Data. Appendix B. Variables and Descriptive Statistics. Appendix C. Imputation Model. Appendix D. Fitted Model Parameter Estimates. Appendix E. Robustness Checks.