This paper introduces the M2K (Music-to-Knowledge) music digital library (MDL) and music information retrieval (MIR) prototyping and evaluation environment to the digital library research community. M2K is being developed as part of the International Music Information Retrieval Systems Evaluation Laboratory project (IMIRSEL). The goal of the IMIRSEL project is the creation of standardized tools and datasets for the scientific evaluation of MDL and MIR systems. M2K plays a central role in the upcoming Music Information Retrieval Evaluation eXchange (MIREX) contest being held over the spring and summer of 2005. MIREX participants will be using M2K to prototype and then submit for formal evaluation their novel approaches to such MDL tasks as artist identification, genre classification, etc