Quality of life (QOL) is a key outcome in patients with congenital heart disease (CHD) because CHD has become a chronic condition accompanied by lifelong impairments. Recently, published studies on QOL in adults with CHD have reported inconsistent findings. Patients' QOL seems to depend on multiple factors and is not solely determined by their heart defect and various medical or demographic characteristics. For instance, evidence suggests that a strong sense of coherence might be an important pathway to improve QOL. However, studies on QOL and its determinants are characterized by important methodological differences and limitations, making it impossible to draw firm conclusions. To fill the gaps in the current evidence base, longitudinal and international research is needed. Furthermore, the research field on QOL in CHD should move on from observational studies to interventional research to guide health professionals in improving QOL.