One of the key transitions in Arabidopsis development occurs as the seedling moves from the dark of the soil to the light it finds above the surface. This transition induces a change in the developmental program – from skotomorphogenesis to photomorphogenesis – that is regulated by the COP1/SPA ubiquitin ligase complex and the PIF family of transcription factors. However, while both COP1/SPA and PIFs show constitutive photomorphogenesis (cop) phenotypes, the relationship between the proteins has remained incompletely understood. Now, Vinh Ngoc Pham, Xiaosa Xu and Enamul Huq address this issue with molecular analysis of cop phenotypes. They first find that the levels of constitutively expressed PIF proteins are decreased in cop1 and spaQ mutants; conversely, overexpression of PIFs partially rescues the mutants’ cop phenotypes. Inhibition of the proteosome prevents PIF degradation, and RNA-seq reveals a cohort of genes commonly regulated by COP1, SPA and PIFs, which surprisingly includes a subset of genes oppositely regulated by COP1/SPA compared with PIFs. Many direct PIF targets are also co-regulated by COP1/SPA, and the positively acting transcription factor HFR1 inhibits the DNA binding activity of PIF1 in the dark by sequestering it. This work therefore revises our understanding of how cop phenotypes are regulated at the molecular level, shedding new light on the crucial transition from skotomorphogenesis to photomorphogenesis.