Chromatin-modifying complexes typically contain signature domains that either have catalytic activity or recognize and bind to specific histone modifications such as acetylation, methylation, and phosphorylation. Despite tremendous progress in this area, much remains to be learned in particular about the mechanistic functions of less well characterized signature domains. One such module is the evolutionary conserved YEATS domain, found in a variety of chromatin-modifying and transcription complexes from yeast to human. Three yeast proteins contain a YEATS domain, including Yaf9, a subunit of both the histone variant H2A.Z deposition complex SWR1-C and the histone acetyltransferase complex NuA4. The three-dimensional structure of the YEATS domain from Yaf9 was solved recently, revealing the existence of three distinct structural regions. One region is characterized by a shallow groove that might constitute a potential acetyl-lysine binding pocket, raising questions about potential protein interaction partners of the Yaf9 YEATS domain.