ImportanceThere is a tension between clinician-led approaches to engagement in advance care planning (ACP), which are effective but resource-intensive, and self-administered tools, which are more easily disseminated but rely on ability and willingness to complete.ObjectiveTo examine the efficacy of computer-tailored print feedback (CTPF), motivational interviewing (MI), and motivational enhancement therapy (MET) on completion of a set of ACP activities, each as compared with usual care.Design, Setting, and ParticipantsThis randomized clinical trial was conducted from October 2017 to December 2020 via telephone contact with primary care patients at a single VA facility; 483 veterans aged 55 years or older were randomly selected from a list of patients with a primary care visit in the prior 12 months, with oversampling of women and people from minoritized racial and ethnic groups. Statistical analysis was performed from January to June 2022.InterventionsMailed CTPF generated in response to a brief telephone assessment of readiness to engage in and attitudes toward ACP; MI, an interview exploring ambivalence to change and developing a change plan; and MET, MI plus print feedback, delivered by telephone at baseline, 2, and 4 months.Main Outcome and MeasuresSelf-reported completion of 4 ACP activities: communicating about views on quality vs quantity of life, assignment of a health care agent, completion of a living will, and submitting documents for inclusion in the electronic health record at 6 months.ResultsThe study included 483 persons, mean (SD) age 68.3 (8.0) years, 18.2% women and 31.1% who were people from minoritized racial and ethnic groups. Adjusting for age, education, race, gender, and baseline stage of change for each ACP, predicted probabilities for completing the ACP activities were: usual care 5.7% (95% CI, 2.8%-11.1%) for usual care, 17.7% (95% CI, 11.8%-25.9%; P = .003) for MET, 15.8% (95% CI, 10.2%-23.6%; P = .01) for MI, P = .01, and 10.0% (95% CI, 5.9%-16.7%; P = .18) for CTPF.Conclusions and RelevanceThis randomized clinical trial found that a series of 3 MI and MET counseling sessions significantly increased the proportion of middle-aged and older veterans completing a set of ACP activities, while print feedback did not. These findings suggest the importance of clinical interaction for ACP engagement.Trial RegistrationClinicalTrials.gov Identifier: NCT03103828