The ICD-10-CA/CCI–based grouping methodologies for ambulatory care (Comprehensive Ambulatory Classification System [CACS]) and acute inpatient care (Case Mix Group+ [CMG+]), along with the associated Resource Intensity Weight (RIW) and Expected Length of Stay (ELOS) indicators, continue to evolve from year to year. In an effort to ensure that historical time series analyses derived from these methodologies are relevant and useful, the Canadian Institute for Health Information (CIHI) is pleased to offer the grouping of up to 5 years of historical data from the Discharge Abstract Database (DAD) and the National Ambulatory Care Reporting System (NACRS).