In the Essentials of Magnetism (EOM) study, staff nurses in 9 of 16 hospitals known to have excellent staffing structures, ie Magnet hospitals, perceived staffing on their units as less than adequate. These hospitals did not fit the Magnet profile when compared to 26 Magnet, Magnet-aspiring, and non-Magnet hospitals. In the EOM study, the process “perception of adequacy of staffing” (PAS) was measured with a single-item indicator. A multi-item scale incorporating the results of a delivery system survey reported here, as well as other factors known to affect PAS, was constructed and evaluated. Results indicate that the 6-item PAS Scale is valid and reliable and is a more accurate measure of PAS than is a single-item indicator. The Magnet hospitals scored significantly higher on all 6 items of the scale than did the comparison hospitals. The 2 Magnet hospitals that did not score in the Magnet profile in the EOM study scored similarly to the Magnet hospital that scored very high in the Magnet profile. Measurement of the PAS process indicates whether staffing structures are viable and enabling and may account for the mixed results seen in some studies assessing the impact of staffing structures on patient outcomes. Discussion includes suggestions on how to promote smooth handoffs and accountability with flex delivery models, and emphasizes the need to evaluate the relationship between staff nurses' perceptions of adequate staffing and patient outcomes.