ObjectivesMost prior advance care planning (ACP) interventions lack integration of the social context of patients' ACP process, which patients indicate is critically important. The current study developed the Planning Advance Care Together (PACT) website to foster inclusion of loved ones in the ACP process. MethodsTo provide feedback about the PACT website, patients with advanced cancer (N = 11), their caregivers (N = 11), and experts (N = 10) participated in semi-structured interviews. Patients and caregivers also completed standardized ratings of acceptability and usability. ResultsOverall, patient (n = 11) and caregiver (n = 11) ratings of acceptability and usability of the website exceeded benchmark cut-offs (≥24 on the Acceptability E-Scale and ≥ 68 on the System Usability Scale). Patients, caregivers, and experts liked the topic of ACP but felt that it could be emotionally challenging. They recommended focusing more on planning and less on end of life. They appreciated being able to include loved ones and recommended adding resources for caregivers. ConclusionsStudy findings support the preliminary usability and acceptability of the PACT website. Findings will be used to inform a modified prototype of the PACT website that is interactive and ready for field testing with patients with advanced cancer and their loved ones. InnovationWe utilized a novel application of the shared mind framework to support patients with advanced cancer in engaging their loved ones in the ACP process.