Background: Pressure injuries (PrIs) cause pain and infection, lengthen institutional care, raise healthcare costs, and hasten death in nursing home (NH) residents. Repositioning residents to offload pressure on tissues is the most common prevention strategy, yetthe optimal interval remains uncertain.Objective: Investigate clinical effectiveness of three nursing-home-wide repositioning intervals (2-,3-, or 4-hours) without compromising PrI incidence in four weeks in adult nursing home residents.Design, Setting, and Participants: Anembedded pragmatic cluster randomized controlled trial was conducted in 9 NHs from a large proprietary system located in 34 states. Each NH was randomly assigned to one of three NH-wide repositioning interval Arms (every 2, 3, or 4 hours). Data were provided for 12-month Baseline and 4-week Intervention during the Turn Everyone And Move for Ulcer Prevention (TEAM-UP) study. Intervention residents were without current PrIs, had PrIrisk (Braden Score) ≥10 (low, mild, moderate, or high risk; not severe risk), and used viable 7” high-density foam mattresses.Methods: Each Arm included three NHs with assigned single repositioning interval as standard care during the 4-week Intervention. Mandatory staff education sessions were provided.A wireless patient monitoring system, using wearable single-use patient sensors, cued staff by displaying resident repositioning need on conveniently placed monitors.Primary outcome was PrI incidence; secondary outcome was staff repositioning compliance fidelity.Results: Eleven hundred residents from 9 NHs were fitted with sensors; 108 of these were ineligible for some analyses due to missing Baseline data. Effective sample size included 992 residents (mean age 78 years [SD13]; 63% female). Pressure injury incidence during the Intervention was 0.0% compared to 5.24% in Baseline, even though Intervention resident clinical risk scores were significantlyhigher (p<0.001). Repositioning compliance for 4-hour repositioning interval (95%) was significantly better than 2- (80%) or 3- (90%) hours (p<.001).Conclusions: This study contributes to understanding alternativerepositioning intervalssuggestingcurrent 2-hour protocolscan be relaxed for many without compromising PrI development. Causal link was not established between three repositioning interval treatments and primary outcome—PrIs; however, no new PrIs developed. Cueing staff may benefit repositioningimplementation; compliance improved as repositioning interval lengthened.Trial Registration: (ClinicalTrials.gov Identifier: NCT02996331).Date: 16/05/2017