Disease self-management is a critical component of maintaining clinical stability for patients with chronic illness. This is particularly evident in the context of heart failure (HF), which is the leading cause of hospitalization for older adults. HF self-management, commonly known as HF self-care, is often performed with the support of informal caregivers. However, little is known about how a HF dyad manages the patient's care together. The purpose of this study was to identify determinants of patient and caregiver contributions to HF self-care maintenance (daily adherence and symptom monitoring) and management (appropriate recognition and response to symptoms), utilizing an approach that controls for dyadic interdependence. This was a secondary analysis of cross-sectional data from 364 dyads of Italian HF patients and caregivers. Multilevel modeling was used to identify determinants of HF self-care within patient-caregiver dyads. Patients averaged 76.2 (SD = 10.7) years old, and a slight majority (56.9%) was male, whereas caregivers averaged 57.4 (SD = 14.6) years old, and about half (48.1%) were male. Most caregivers were adult children (48.4%) or spouses (32.7%) of patients. Both patients and caregivers reported low levels of HF maintenance and management behaviors. Significant individual and dyadic determinants of self-care maintenance and self-care management included gender, quality of life, comorbid burden, impaired ADLs, cognition, hospitalizations, HF duration, relationship type, relationship quality, and social support. These comprehensive dyadic models assist in elucidating the complex nature of patient-caregiver relationships and their influence on HF self-care, leading to more effective ways to intervene and optimize outcomes.