Assessment of the potential environmental impact of an in situ leach (ISL) project is the first step in the permission and licensing process. An Environmental Impact Assessment (EIA) serves as the basis for preparing an Environmental Impact Statement (EIS), which in turn identifies the potential environmental and socioeconomic impact of a proposed project and outlines measures to mitigate this impact. The EIS review process serves to inform the public about a proposed project as well as to provide regulatory agencies with assurance that ISL technology will comply with environmental standards, and that project sites can be rehabilitated to pre-mining use. This publication provides a step-by-step description of project parameters that must be addressed in conducting an EIA and preparing an EIS. It also includes EIA/EIS case histories for current operations in Australia, the Czech Republic, Kazakhstan and the United States of America. The publication will be useful to companies considering the development of ISL projects and to regulatory personnel who are responsible for writing environmental regulations and licensing ISL projects.