Background: Patients with unplanned dialysis must perform self-management behaviors tomaintain their health in the community after discharge. Understanding the factors that predict the postdischarge self-management behaviors of patients with unplanned dialysis can assist nurses to implement appropriate discharge plans for this population. Purpose: This study was designed to predict the effects of uncertainty in illness, self-care knowledge, and social-supportrelated needs during hospitalization on the self-management behaviors of patients with unplanned dialysis during their first 3 months after discharge from the hospital. Methods: One hundred sixty-nine patientswith unplanned dialysis from the nephrology department of a medical center in Taiwan were enrolled in this prospective study using convenience sampling. At hospital admission, demographic, uncertainty in illness, self-care knowledge, and social support information was collected using a structured questionnaire. Information on self-management behavior was collected at 3 months postdischarge when the patients visited outpatient clinics. Results: Hierarchical multiple regression analyses showed that self-care knowledge, uncertainty in illness, and social support were important predictors of self-management behaviors at 3 months postdischarge, explaining 65.6% of the total variance in self-management behaviors. Social support increased the variance in self-management behaviors by 27.9%. Conclusions/Implications for Practice: Comprehensive discharge planning to improve the postdischarge self-management behaviors of patients with unplanned dialysis should involve interventions to improve self-care knowledge, reduce uncertainty in illness, and increase social support. Building social support should be given priority attention.