Cochrane Reviews take a systematic and comprehensive approach to identifying studies that meet the eligibility criteria for the review. This chapter outlines some general issues in searching for studies; describes the main sources of potential studies; and discusses how to plan the search process, design and carry out search strategies, manage references found during the search process, correctly document the search process and select studies from the search results. This chapter aims to provide review authors with background information on all aspects of searching for studies so that they can better understand the search process. All authors of systematic reviews should, however, identify an experienced medical/healthcare librarian or information specialist to provide support for the search process. The chapter also aims to provide advice and guidance for medical/healthcare librarians and information specialists (within and beyond Cochrane) involved in the search process to identify studies for inclusion in systematic reviews.