The increasing survival of patients with congenital heart defects into adulthood has created a rapidly expanding and heterogeneous population of adults with congenital heart disease, now exceeding pediatric cases in prevalence. These patients present unique anatomical and physiological challenges resulting from previous surgeries, residual defects, and age-related comorbidities. This chapter provides a modern, evidence-based perspective on tailored interventional strategies in ACHD, emphasizing the critical shift from standardized pediatric approaches to individualized adult care models. We outline key distinctions between pediatric and adult CHD patients, address the challenges of care transition, and present diagnostic strategies essential for risk stratification and procedural planning. The chapter systematically reviews intervention options across various conditions including atrial and ventricular septal defects, aortic coarctation, tetralogy of Fallot, and transposition of the great arteries, integrating surgical, transcatheter, and hybrid approaches. Clinical decision-making is anchored in lesion-specific anatomy, surgical history, imaging findings, and patient-centered goals. The chapter promotes a paradigm of personalized care that adapts to each patient’s evolving needs and underscores the necessity of specialized ACHD centers. As the ACHD population continues to age, long-term surveillance, innovation in technology, and individualized therapy will be essential to improving prognosis and quality of life.