Abstract: The field of fish passage is beset by claims of performance that are often either unsubstantiated, or quantified in ways that contain logical flaws, oversights, or alternative interpretations. Claims of successful passage based on fishway counts are widespread, but typically fail to ask the basic question of how many fish tried to pass but failed, how many attempts did it take to pass, and how much effort was expended trying to pass for fish that passed as well as for those that failed. Understanding the duration of effort and when fish are available to pass is essential to identifying causes of fishway failure as well as for identifying truly effective structures. In order to properly understand the effectiveness of fishways it is necessary to measure three distinct phases of passage: discovery, or approach to the fishway entrance; entry into the fishway; and ascent (or descent in the case of downstream passage). By measuring the times, frequencies, durations, and fates of each of these steps it is possible to accurately measure performance of each one, and also to determine locations and conditions that limit passage performance. Time-to-event analysis—a suite of tools developed for survival studies—is ideally suited for providing these metrics, and provides least biased estimates of performance while controlling for conditions that change over time.