Over the past 15 years, clinical studies have demonstrated methods of expediting liberation from mechanical ventilation. Since endotracheal intubation and positive-pressure ventilation engender significant risks that increase with time, personnel who care for critically ill patients are obliged to liberate the patient on the first day on which success is likely. Weaning parameters are measurements of physiologic respiratory parameters that have been used to guide such weaning decisions. Recent reviews1–2 and an international consensus statement3 have discussed the published literature examining the clinical predictive utilities of various weaning parameters. No weaning parameter is perfectly predictive,3–4 but some may be useful when used in protocols to expedite weaning and to reduce the duration of mechanical ventilation.5–6 In this issue of CHEST (see page 1947), Hoo and Park administered questionnaires to 102 respiratory therapists who practice in nine Los Angeles-area ICUs, interrogating them about the weaning parameters used in their clinical practices. Despite the abundance of scientific reports published in the past decade,,1–3 the data reveal a startling degree of chaos in this area. Some parameters (ie, maximal inspired pressure, respiratory frequency, tidal volume [Vt], and minute ventilation) were measured and recorded by > 90% of respondents, but these parameters in themselves are not highly predictive of weaning outcomes. The ƒ/Vt ratio, arguably the most predictive parameter,,3–4 can be computed but was reported specifically by < 20% of respondents. This suggests that it may not have been used to guide weaning decisions. Moreover, the time of day at which parameters were measured and the methods of measurement were not uniform. Frequently, parameters were not measured using published techniques, which reduces the predictive utility of the various measures. For example, only 3 of 106 respondents measured the ƒ/Vt properly with a spirometer during a couple of minutes of T-piece breathing.,7–8 There was also significant variability in the methodology used to measure the maximum inspiratory pressure. These findings deserve comment.