Ethylene controls many aspects of plant growth, development and response to the environment. Many ethylene-mediated processes have significant economic consequence. While much effort has been focused on fruit ripening, ethylene also mediates such economically significant processes as flower and fruit abscission, senescence and pathogen defense. Ethylene action is initiated by binding to a family of receptors. We have focused much of our effort on characterization of the receptor gene family of tomato. Beyond its obvious commercial significance, tomato is an outstanding model system for study of multiple ethylene-mediated processes. We have used transgenic lines to evaluate the roles of the individual members of the receptor family and elucidate the mechanisms of signal transduction. We have established that many important processes can be modified by altering receptor gene expression. However, the manipulation of ethylene signaling is not straightforward. Because it is involved in so many processes essential for plant maturation, ethylene signaling must be modified with caution. Nonetheless, as our knowledge of how receptors function increases, mechanisms for both molecular and chemical means to crop improvement are being achieved.