Importance: Postoperative delirium (POD) is a common condition for older adults, contributing to their functional decline.; Objective: To investigate the effectiveness of the Tailored, Family-Involved Hospital Elder Life Program (t-HELP) for preventing POD and functional decline in older patients after a noncardiac surgical procedure.; Design, Setting, and Participants: A 2-arm, parallel-group, single-blind, cluster randomized clinical trial was conducted from August 24, 2015, to February 28, 2016, on 6 surgical floors (gastric, colorectal,