This report on environmental assessment (EA) is the third in a series to be pub lished by the World Bank’s Inspection Panel drawing on the main lessons that have emerged from its caseload over 23 years. With these reports, the Panel aims to contribute to institutional learning at the World Bank and in the larger development community by highlighting areas where improvements can enhance the social, environmental, and overall sustainability of Bank-funded operations, further development effectiveness, and enhance transparency. The Inspection Panel was created in 1993 by the World Bank’s Board of Executive Directors to receive and investigate complaints submitted by peo ple actually or potentially suffering harm allegedly caused by Bank projects. Since then, the Panel has received 118 Requests for Inspection. Of those, 87 have been registered and 34 investigated. Of the 34 cases investigated, 29 have involved issues related to environmental assessment, defined as the process of identifying, predicting, evaluating, and mitigating the natural, social, and other relevant impacts (both positive and neg ative) of development proposals prior to making major decisions and commit ments. Two of the Panel’s eligibility reports were also considered for this publication to illustrate additional important lessons. These 31 cases covered 27 countries in six regions. Most of the issues represented in these cases involved adequate screening and scoping, and the consideration of both social and natu ral impacts. While all relevant Panel cases were studied as part of this report, a special emphasis was put on drawing lessons from cases within the past decade. This report draws the following main conclusions from the cases: • Panel cases show the importance of a continuous environmental assess ment process throughout the project cycle. This includes conducting quality impact assessments during project preparation as well as adequate follow-up on issues arising during implementation. Thorough assess ments that integrate natural and social impacts are both required and essential to anticipate issues, plan proper mitigation measures, deal with problems that arise in an effective and timely manner, and ensure project sustainability in the long term. • Strong supervision is crucial. This includes on-site verification when problems are identified, multidisciplinary expertise that goes beyond engineering to environmental and social issues, and continuous dialogue to close potential gaps between the reality on the ground and perspectives of the project team. • Many of the issues found in Panel cases relate to the importance of con sidering the social dimensions of a project, and the Panel’s experience suggests that lapses in analyzing social risks and impacts can create or exacerbate already complex situations. • Not only high-risk (Environmental Category A) projects have the poten tial to cause significant harm. The Panel has received Requests related to Emerging Lessons Series: Environmental Assessment v projects in all environmental categories and has investigated projects with Category A (18) and B (9) designations. Panel cases show that it is critical to identify, mitigate, and monitor all project risks, regardless of the project’s environmental categorization. • Panel cases have positively influenced World Bank practices related to environmental assessment. In response to Panel investigations, the Bank has provided clarifications related to the application of the Bank’s Policy on Environmental Assessment and issued guidelines to staff on how to address relevant policy issues. Some recent examples include the issuance of a guidance note on managing labor influx risks in World Bank projects, as well as the creation of a Gender-Based Violence (GBV) Taskforce to develop recommendations for the institution on how to prevent and respond to GBV in Bank projects. Finally, and as stated in previous Emerging Lessons Series reports, Panel cases tend to highlight challenging projects where things went wrong. Therefore, these 31 cases are not necessarily reflective of the Bank’s entire portfolio. Nevertheless, the lessons are important. This exercise is intended to help build the institutional knowledge base, enhance accountability, foster better project results and, ultimately, contribute to more effective develop ment with shared prosperity for all.