This article is based on a course on how to use Moys classification scheme,1 delivered by Helen Garner and Felicity Staveley-Taylor on behalf of the British and Irish Association of Law Librarians (BIALL) in November 2022. The article, which is also written by Helen and Felicity, provides guidance on how to use Moys classification, explaining the features that enable the scheme to be expanded to accommodate new subject areas. The article also explains some of the features which ensure the scheme remains relevant to legal libraries today. Sections from the classification scheme, as published in the fifth edition, appear in the article text. In addition, any references to page numbers are to the fifth edition.