Background Many patients have three primary goals for how treatment decisions are made for them in the event of decisional incapacity. They want to be treated consistent with their preferences and values, they want their family to be involved in making decisions, and they want to minimize the stress on their family. The present paper investigates how patients’ beliefs about surrogate decision-making influence which of these three goals they prioritize. Methods: Quantitative survey of 1,169 U.S. patients to assess their beliefs about surrogate decision-making, and how these beliefs influence patients’ priorities for surrogate decision-making. Results: Most patients believed that families in general (68.8%) and their own family in particular (83.4%) frequently, almost always, or always know which treatments the patient would want in the event of incapacity. Patients with these beliefs were more likely to prioritize the goal of involving their family in treatment decision-making over the goal of minimizing family stress. Most patients (77.4%) also believed their family would experience significant stress from helping to make treatment decisions. However, patients’ priorities were largely unchanged by this belief. Conclusions: Prior reports suggest that patients overestimate the extent to which their family knows which treatments they want in the event of decisional incapacity. The present analysis adds that these patients might be more likely to prioritize the goal of involving their family in treatment decision-making, even when this results in the family experiencing significant distress. This finding highlights that patients’ misinformed beliefs about their family’s knowledge might influence patients’ priorities for surrogate decision-making, raising important questions for clinical practice, policy, and future research. Supplemental data for this article is available online at https://doi.org/10.1080/23294515.2021.1983665