Workshop description All evaluators deal with unintended events that foul their evaluation plans. Either the program does not work as planned, or the evaluation does not work as planned, or both. Usually we treat these situations as fires, i.e. we exercise our skills to meet the crisis. This workshop steps back from crisis mode and presents a systematic treatment of why these situations pop up, the continuum from “unforeseen” to “unforeseeable”, tactics that can be used along the continuum, and why caution is needed because anything we do to minimize the effect of surprise may be the cause of yet other difficulties. The intent of the workshop is twofold. First, to provide individual attendees with skills and knowledge they can employ in their own practice. Second, to further a community of interest among evaluators dedicated to developing systematic understanding of the phenomenon of unanticipated events that threaten the integrity of evaluation.