ContextPersonal and interpersonal factors may be influential in a person's decision to engage in advance care planning (ACP), including completion of ACP documentation. ObjectivesTo conduct a cross-sectional survey of older adults accessing Australian general practices, hospitals, and residential aged care facilities, with the aim of describing associations between personal and interpersonal factors and self-reported ACP documentation completion. MethodsEligible participants included in a national health record audit were approached to complete a survey measuring demographic and health characteristics, preferences for care, worries about the future, and experiences talking with others about ACP and completing ACP documentation. ResultsOf 1082 people eligible to participate in the survey, 507 completed the survey (response rate = 47%; median age 82 years) and 54% (n = 272) reported having completed ACP documentation. Having ever discussed ACP with other people (anyone) or a doctor were both significant predictors of ACP documentation completion, whereas having previously spoken specifically to a partner about ACP, currently living with children compared to living alone, and being aged 55–69 versus 90–99 years were associated with reduced odds of ACP documentation completion. ConclusionApproximately half the participants reported having completed ACP documentation. The strongest predictor of ACP documentation completion was having spoken to anyone about ACP followed by having spoken to a doctor about ACP. These findings suggest that discussions about ACP are an important part of the process of completing ACP documentation.