Objective: To longitudinally assess whether risk adjustment in Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy (ALPPS) occurred over time and is associated with postoperative outcome. Background: ALPPS is a novel 2-stage hepatectomy enabling resection of extensive hepatic tumors. ALPPS has been criticized for its high mortality, which is reported beyond accepted standards in liver surgery. Therefore, adjustments in patient selection and technique have been performed but have not yet been studied over time in relation to outcome. Methods: ALPPS centers of the International ALPPS Registry having performed amp;gt;= 10 cases over a period of amp;gt;= 3 years were assessed for 90-day mortality and major interstage complications (amp;gt;= 3b) of the longitudinal study period from 2009 to 2015. The predicted prestage 1 and 2 mortality risks were calculated for each patient. In addition, questionnaires were sent to all centers exploring center-specific risk adjustment strategies. Results: Among 437 patients from 16 centers, a shift in indications toward colorectal liver metastases from 53% to 77% and a reverse trend in biliary tumors from 24% to 9% were observed. Over time, 90-day mortality decreased from initially 17% to 4% in 2015 (P = 0.002). Similarly, major interstage complications decreased from 10% to 3% (P = 0.011). The reduction of 90-day mortality was independently associated with a risk adjustment in patient selection (P amp;lt; 0.001; OR: 1.62; 95% CI: 1.36-1.93) and using less invasive techniques in stage-1 surgery (P = 0.019; OR: 0.39; 95% CI: 0.18-0.86). A survey indicated risk adjustment of patient selection in all centers and ALPPS technique in the majority (80%) of centers. Conclusions: Risk adjustment of patient selection and technique in ALPPS resulted in a continuous drop of early mortality and major postoperative morbidity, which has meanwhile reached standard outcome measures accepted for major liver surgery.