Transcriptional feedback loops are central to the architecture of eukaryotic circadian clocks. Models of the Arabidopsis circadian clock have emphasized transcriptional repressors, but recently Myb-like REVEILLE (RVE) transcription factors have been established as transcriptional activators of central clock components, including PSEUDO-RESPONSE REGULATOR5 (PRR5) and TIMING OF CAB EXPRESSION1 (TOC1).