Music materials, particularly scores and recordings, pose unique demands that must be considered for their successful discovery. Some of the discoverability challenges of music materials in public search interfaces can be addressed simply by ensuring that needed bibliographic description fields are appropriately displayed and indexed in discovery interfaces. Other problems are more difficult to solve. This Music Discovery Requirements document explores the issues and gives concrete recommendations for discovery interfaces. Given that most libraries will be dealing with databases containing large bodies of legacy data recorded according to AACR2 and encoded in MARC, particular attention is paid to MARC data and to AACR2; RDA is addressed to the extent possible. The discussions and recommendations will be useful to those creating or guiding the development of discovery interfaces that will facilitate access to music materials. Furthermore, because the document identifies areas where deficient data create particular problems for discovery, those inputting or creating standards for data can use this document to identify areas with particular needs for fuller, more consistent data.