The past decade has been incredibly productive for ethylene researchers. Major components in the ethylene signaling pathway in plants have been identified and characterized. The past year's contributions include the crystallographic analysis of the Arabidopsis ETR1 receiver domain, antisense studies of the tomato ethylene receptor genes LeETR4 and NR, and the cloning and functional characterization of several Arabidopsis EREBP-related transcription activators and repressors, and of an EIN3-ortholog of tobacco. Additional evidence for the interconnection of the ethylene and auxin responses was provided by the cloning and characterization of Arabidopsis NPH4. Finally, the first discovery of ethylene responsiveness in an animal species implied a more universal role for ethylene than previously thought.