RATIONALE: Several intensive care unit (ICU) organizational practices have been associated with improved patient outcomes. However, the uptake of these evidence-based practices is unknown. OBJECTIVES: To assess diffusion of ICU organizational practices across the state of Pennsylvania. METHODS: We conducted two web-based, cross-sectional surveys of ICU organizational practices in Pennsylvania acute care hospitals, in 2005 (chief nursing officer respondents) and 2014 (ICU nurse manager respondents). MEASUREMENTS AND MAIN RESULTS: Of 223 eligible respondents, nurse managers from 136 (61%) medical, surgical, mixed medical-surgical, cardiac, and specialty ICUs in 98 hospitals completed the 2014 survey, compared with 124 of 164 (76%) chief nursing officers in the 2005 survey. In 2014, daytime physician staffing models varied widely, with 23 of 136 (17%) using closed models and 33 (24%) offering no intensivist staffing. Nighttime intensivist staffing was used in 37 (27%) ICUs, 38 (28%) used nonintensivist attending staffing, and 24 (18%) had no nighttime attending physicians. Daily multidisciplinary rounds occurred in 93 (68%) ICUs. Regular participants included clinical pharmacists in 68 of 93 (73%) ICUs, respiratory therapists in 62 (67%), and advanced practitioners in 37 (39%). Patients and family members participated in rounds in 36 (39%) ICUs. Clinical protocols or checklists for mechanically ventilated patients were available in 128 of 133 (96%) ICUs, low tidal volume ventilation for acute respiratory distress syndrome in 54 of 132 (41%) ICUs, prone positioning for severe acute respiratory distress syndrome in 37 of 134 (28%) ICUs, and family meetings in 19 of 134 (14%) ICUs. Among 61 ICUs that responded to both surveys, there was a significant increase in the proportion of ICUs using nighttime in-ICU attending physicians (23 [38%] in 2005 vs. 30 [49%] in 2014; P = 0.006). CONCLUSIONS: The diffusion of evidence-based ICU organizational practices has been variable across the state of Pennsylvania. Only half of Pennsylvania ICUs have intensivists dedicated to the ICU. Variable numbers use clinical protocols for life-saving therapies, and few use structured family engagement strategies. In contrast, the diffusion of non-evidence-based practices, including overnight ICU attending physician staffing, is increasing. Future research should focus on promoting implementation of organizational evidence to promote high-quality ICU care.