Human gene expression patterns are controlled and coordinated by the activity of a diverse array of epigenetic regulators, including histone methyltransferases, acetyltransferases, and chromatin remodelers. Deregulation of these epigenetic pathways can lead to genome‐wide changes in gene expression, with serious disease consequences. In recent years, research has suggested that cross talk between genomic (i.e., for example, mutations, translocations) and epigenomic factors may drive the etiology of both hematologic malignancies and solid tumors. Current work in translational research seeks to identify epigenetic regulators whose aberrant activity contributes to oncogenesis, including the histone methyltransferases DOT1L and EZH2 and the bromodomain‐containing BET family, and to develop drugs that inhibit the aberrant activity of these regulators. Preclinical and clinical studies using small‐molecule inhibitors of epigenetic regulators have underscored their value for therapeutic intervention, and these inhibitors can also be used to drive further studies into dissecting the functions of epigenetic factors in normal and cancer cells.