This volume provides methods used to investigate histone methyltransferase function. Chapters guide readers through a comprehensive set of approaches that detail phylogenetic diversity, histone demethylase activities in vitro, generating chromatin substrates, auto-methylation, quantification of metabolites, protein purification, crystallization, X-ray structure, cryogenic electron microscopy, assessing genome-wide patterns, CUT&Tag in mouse embryonic tissues, chemical biology approaches, peptide SPOT arrays, nascent chromatin capture, ectopic protein tethering, computational models, and development of methyltransferase inhibitors. Written in the format of the highly successful Methods in Molecular Biology series, each chapter includes an introduction to the topic, lists necessary materials and reagents, includes tips on troubleshooting and known pitfalls, and step-by-step, readily reproducible protocols. Authoritative and cutting-edge, Histone Methyltransferases: Methods and Protocols aims to be a useful and practical guide to new researchers and experts looking to expand their knowledge.