ABSTRACT This first competitive renewal application seeks to continue NHLBI funding for a T32 Training Grant at one of the premier fellowship training programs in Pediatric Pulmonary Medicine in the United States (U.S.). The specialty focuses on respiratory diseases, the most common cause of emergency department visits and hospitalizations among children in the U.S. Approximately 1,194 board-certified pediatric pulmonologists (or only ~4.6% of the 25,957 board certified pediatric subspecialists in 2019) serve this large population of children. Few pediatric pulmonologists have had research mentors or academic role models with a strong track record of excellence in research. In spite of a well-recognized need to train more scientists and physician-scientists in this field, there are currently only four T32 training grants in Pediatric Pulmonary Medicine in the U.S. Over the last decade, our fellowship program has markedly contributed to the small cadre of physician-scientists and scientists in pediatric pulmonary medicine. Such contributions have been enhanced by NHLBI funding of our training program since 2016, as all 7 graduates of this T32 Training Program over the past 4.5 years are in an academic track and have been highly productive, as measured by the number of publications directly resulting from participation in the T32 program, as well as by subsequent funding from intramural and/or extramural sources, including career development awards from the NHLBI, the American Heart Association, and the Cystic Fibrosis Foundation. Our interdisciplinary training program is built on the strong research environment at the University of Pittsburgh and provides trainees with the fundamental tools and skills to design, implement, and interpret meaningful research projects. Faculty mentors are highly interactive, academically productive, and truly dedicated to the training of scientists and physician-scientists. The goal of this proposal is to continue to provide a prime source of well-trained physician-scientists and Ph.D. scientists to conduct cutting-edge research in pediatric pulmonary diseases. To achieve this mission, we seek to provide, within a single center, the research role models, mentorship, and rich environment necessary for nurturing such individuals and ensuring their success.