Introduction: Nursing professionals develop situation-specific theories to describe, explain, and provide comprehensive care during a family member’s transition to the caregiver role. Objective: To develop a situation-specific theory about the transition to the role of family caregiver of older adults after a stroke. Methodology: The integrating approach by Meleis and Im was applied, which consists of five stages: 1) Description of the context and target population, 2) Verification of assumptions regarding the philosophical stance, 3) Exploration of multiple sources, 4) Theorization of concepts, and 5) Proposal of empirical indicators for validation and verification. Results: The prescriptive theory was developed in the light of Afaf Meleis’ Theory of Transitions and was supported by an exhaustive literature review, with four underlying concepts: Situational transition to the family caregiver role, Care-related knowledge and skills, Self-confidence and coping in adopting the caregiver role, and Nursing therapeutic education. The following assumption emerges from these concepts: a healthy transition to the family caregiver role is directly dependent on the care-related knowledge and skills provided by Nursing therapeutic education to develop self-confidence and coping in adopting the caregiver role. Conclusions: The proposal provides a conceptual framework that identifies the transition challenges and needs faced by family caregivers to adopt the role of caregivers of older adults after a stroke.