Understanding of mammalian enhancers is limited by the lack of a technology to rapidly and thoroughly test the cell type-specific function. Here， we use a nuclease-deficient Cas9 (dCas9)-histone demethylase fusion to functionally characterize previously described and new enhancer elements for their roles in the embryonic stem cell state. Further， we distinguish the mechanism of action of dCas9-LSD1 at enhancers from previous dCas9-effectors.