Patients with congenital heart disease (CHD) require uninterrupted lifelong specialized cardiac care, yet the transition years are a vulnerable time for these patients. Transition programs offer structured support to patients with CHD with the aim of improving CHD knowledge, independence in care, and providing an uninterrupted transfer process and integration into accredited adult congenital heart disease (ACHD) programs. Transition has three components: preparation, transfer and integration. The main barriers to successful transition program implementation are time and resources to complete transition practices and there is no best model for transition programs. Patients with CHD in the United States (US) have a lower occurrence of transfer to ACHD programs, and they experience more gaps in care during the transition years compared with Canada and Europe. Structured transfer processes to ACHD programs are common in Europe, but these, and overall transition practices in the US are not well understood. The purpose of this dissertation was to test a low resource intervention to facilitate patient preparation, identify factors that improve effective transfer, and evaluate transition practices in the US.