International Standard Musical Work Code (ISWC) is a unique identifier for musical works, similar to ISBN. It is adopted as international standard ISO 15707. The ISO subcommittee with responsibility for the standard is TC 46/SC 9.

Each code is composed of three parts:

Currently, the only prefix defined is "T", indicating Musical works. However, additional prefixes may be defined in the future to expand the available range of identifiers and/or expand the system to additional types of works.

ISWC identifiers are commonly written the form T-123.456.789-Z. The grouping is for ease of reading only; the numbers do not incorporate any information about the work's region, author, publisher, etc. Rather, they are simply issued in sequence. These separators are not required, and no other separators are allowed.

The first ISWC was assigned in 1995, for the song "Dancing Queen" by ABBA; the code is T-000.000.001-0.

To register an ISWC, the following minimal information must be supplied:

Note: an ISWC identifies works, not recordings. ISRC can be used to identify recordings. Nor does it identify individual publications (e.g. issues of a recording on physical media, sheet music, broadcast at a particular frequency/modulation/time/location...)