On the Cover: Chemical genetics has emerged as a powerful tool for defining gene functions, dissecting complex biological pathways, and elucidating the molecular mechanisms of developmental processes. In this issue, Blackwell and Zhao (pp 448–455) give a general introduction to chemical genetics, analyze the advantages and challenges of this approach, and highlight the abundant opportunities to use this approach in plant biology. The cover graphic provides an example of the dramatic effects small molecules can have on plant development: Arabidopsis seedlings grown on Murashige and Skoog media containing 25µM of the small molecule sirtinol develop striking trumpet-shaped organs after three weeks. Through a combination of chemical and classical genetic techniques, the authors have shown that sirtinol constitutively activates auxin signaling in Arabidopsis. When the plant is removed from sirtinol and grown on untreated Murashige and Skoog media, the plant assumes wild-type growth and normal true leaves develop after an additional two weeks. The ability to modulate plant development in such a timed and reversible manner demonstrates the potential utility of chemical genetics in dissecting developmental processes.