This paper reports on the first phase of the research of the International Society for Knowledge Organization (ISKO) Working Group on subject access metadata in library discovery systems. The survey aimed to discover how research libraries provide subject searching support to users. Many libraries use Knowledge Organizing Systems (KOSs) such as general subject headings and classification systems, subject-specific thesauri, and other controlled vocabularies. However, there is a concern that many discovery systems in libraries do not provide easy and seamless access to this enriched metadata to facilitate searching. This investigation aimed to identify the subject searching features offered to users and to explore the barriers to their use. The second part of the investigation will consult providers of discovery systems to find out how these features could be made more accessible. A final phase of the investigation will consult users and their representatives about what kind of support and interface features and functionalities would be appropriate for them. A survey of 116 academic and research libraries in 34 countries revealed a strong emphasis on the use of discovery systems, although many libraries still rely on OPACs as the primary user interface for subject searching. A variety of library management systems incorporating discovery systems included suppliers such as Ex-Libris, Sirsi-Dynix, Aleph, EBSCO, Koha, and OCLC. Most of the libraries surveyed provide some level of training and support, although this varies from one-on-one support, to formal courses, online courses, or as part of orientation sessions for new users. General KOSs such as Library of Congress Subject Headings (LCSH), Dewey Decimal Classification (DDC), Universal Decimal Classification (UDC) and the Chinese Library Classification were frequently mentioned. Medical Subject Headings (MeSH) was the most frequently-mentioned domain-specific system. Librarians reported the following barriers to the use of KOSs as: lack of familiarity with a KOS, complexity and lack of natural language access in case of classification, language barriers, and searching interface issues. The ultimate goal of this research will be to develop a set of guidelines for research and academic libraries about providing easy and seamless access to enriched subject metadata via library discovery systems.