Identifying the approach used by those revision experts par excellence--that is, professional editors--should enable researchers to better grasp the revision process. To further explore this hypothesis, the author conducted research among professional editors, six of whom she filmed as they engaged in their practice. An analysis of their work approach strategies showed their detection strategies to consist in anticipating errors and in comparing the author's text with the editor's knowledge, which appears in a range of states: certitude, uncertainty, and ignorance. Furthermore, the participating editors used problem-solving strategies to automatically solve more than half of the problems encountered in the text. Otherwise, they used immediate or postponed strategies. This description of professional editors in action opens a number of avenues for the further research and development of in-class instruction of self-revision and professional editing. (Contains 7 tables, 1 figure, and 2 notes.) [Appended to this document is "The Professional Editor's Revision Process: A Linear Model."]