Photomorphogenesis is a critical plant developmental process that involves light-mediated transcriptome changes, histone modifications, and inhibition of hypocotyl growth.However, the chromatin-based regulatory mechanism underlying this process remains largely unknown.We identify ENHANCED PHOTOMORPHOGENIC 1 (EPP1), previously known as PICKLE (PKL), an ATP-dependent chromatin remodeling factor of the Chromodomain/Helicase/DNA-binding family, as a repressor of photomorphogenesis in Arabidopsis.