Pediatric cardiac anesthesiology has developed as a subsubspecialty of anesthesiology over the past 70 years. The evolution of this specialty has led to the establishment in 2005 of a dedicated professional society, the Congenital Cardiac Anesthesia Society (CCAS). By 2010, multiple training pathways for pediatric cardiac anesthesia emerged. Eight programs in the United States offered advanced pediatric cardiac anesthesia with variable duration, ranging from 3 to 12 months. Other programs offered a combined fellow/staff position for 1 year. The need for a standardized training pathway was recognized by the Pediatric Anesthesia Leadership Council (PALC) and CCAS in 2014. Specifically, it was recommended that pediatric cardiac anesthesiology be a second, 12-month advanced fellowship following pediatric anesthesia to acquire skills unique from those acquired during a pediatric anesthesia fellowship. This was reiterated in 2018, when specific pediatric cardiac anesthesia training milestones were developed through consensus by the CCAS leadership. However, given the continuous increasing demand for well-trained pediatric cardiac anesthesiologists, it is essential that a supply of comprehensively trained physicians exists. High-quality training programs are therefore necessary to ensure excellent clinical care and enhanced patient safety. Currently, there are 23 programs offering one or more positions for 1-year pediatric cardiac anesthesia fellowship. Due to the diverse curriculum and evaluation process, formalization of the training with accreditation through the Accreditation Council for Graduate Medical Education (ACGME) was the obvious next step. Initial inquiry started in April 2020. The ACGME recognized pediatric cardiac anesthesia as a subsubspecialty in February 2021. The program requirements and milestones for the 1-year fellowship training were developed in 2021 and 2022. This special article reviews the history of pediatric cardiac anesthesia training, the ACGME application process, the development of program requirements and milestones, and implementation.