To evaluate process metrics and outcomes after implementation of the “Rethinking Critical Care” ICU care bundle in a community setting. Retrospective interrupted time-series analysis. Three hospitals in the Kaiser Permanente Northern California integrated healthcare delivery system. ICU patients admitted between January 1, 2009, and August 30, 2013. Implementation of the Rethinking Critical Care ICU care bundle which is designed to reduce potentially preventable complications by focusing on the management of delirium, sedation, mechanical ventilation, mobility, ambulation, and coordinated care. Rethinking Critical Care implementation occurred in a staggered fashion between October 2011 and November 2012. We measured implementation metrics based on electronic medical record data and evaluated the impact of implementation on mortality with multivariable regression models for 24,886 first ICU episodes in 19,872 patients. After implementation, some process metrics (e.g., ventilation start and stop times) were achieved at high rates, whereas others (e.g., ambulation distance), available late in the study period, showed steep increases in compliance. Unadjusted mortality decreased from 12.3% to 10.9% (p < 0.01) before and after implementation, respectively. The adjusted odds ratio for hospital mortality after implementation was 0.85 (95% CI, 0.73-0.99) and for 30-day mortality was 0.88 (95% CI, 0.80-0.97) compared with before implementation. However, the mortality rate trends were not significantly different before and after Rethinking Critical Care implementation. The mean duration of mechanical ventilation and hospital stay also did not demonstrate incrementally greater declines after implementation. Rethinking Critical Care implementation was associated with changes in practice and a 12-15% reduction in the odds of short-term mortality. However, these findings may represent an evaluation of changes in practices and outcomes still in the midimplementation phase and cannot be directly attributed to the elements of bundle implementation.