Histone acetyltransferases (HATs) are a class of epigenetic enzymes involved in critical cellular processes like nucleosome assembly, DNA damage repair, and transcriptional regulation. HATs are implicated in many human pathologies including cancers. This chapter describes essential experimental considerations for performing high-throughput screening and follow-up assays, and offers practical strategies for assay optimization and validation. Illustrative walkthroughs for several HAT assay formats are provided. This content should be useful for those performing HTS assays, orthogonal assays, and counter-screens involving HATs in the context of drug discovery, chemical biology, and molecular pharmacology.