To be useful and retrievable, collections of publications, documents, artifacts, and specimens in libraries, archives, and museums (LAMs) need to be feasibly organized and presented. This is done in a variety of ways. Books in libraries are sorted on shelves in repositories and described in, and accessible through, catalogues and indexes; documents in archives are organized and retrievable through a variety of search protocols and tools; objects in museums are organized in storerooms and described and displayed in catalogues and various exhibitions. These doings go by the name knowledge organization (KO). Due to different commissions, traditions, and material conditions, LAM institutions have developed diverse routines, techniques, and tools to work with KO. In this text, we will trace some historical roots and some challenges and opportunities that new technologies and societal situations bring to the KO work of LAM institutions.