Earlier this year, Richard Young and colleagues reported identification of clusters of enhancers, called super-enhancers, which are bound by the Oct4, Sox2 and Nanog transcription factors and the Mediator complex in embryonic stem cells (ESCs) (Cell 153, 307–319, 2013). They showed that super enhancers can be identified in other cell types, are specific to cell type and are located near genes known to control cell identity. Now, Francis Collins and colleagues report identification of long 'stretch' enhancers that are cell-type specific and are associated with cell-type–specific expression of nearby genes (Proc. Natl. Acad. Sci. USA 110, 17921–17926, 2013). These authors profiled histone H3 modifications and RNA expression in isolated human pancreatic islets and performed analyses with published histone profiles from nine other cell types. They tested two islet stretch enhancers for functional activity in transgenic mice and showed that they drive expression in pancreatic primordium. In addition, Young and colleagues now report a catalog of super-enhancers in 86 human cell types (Cell doi:10.1016/j.cell.2013.09.053, 10 October 2013). They use genome-wide profiles of H3K27ac, which they show is the most strongly predictive chromatin mark for super-enhancers in ESCs, and use this catalog to infer candidate master transcription factors that regulate cell identity in all 86 cell types.