The Development and Pathology working group was charged with reviewing the present knowledge, gaps in understanding, and areas for further studies in a broad range of themes. These themes in pulmonary vascular biology and pathobiology involved: 1) pulmonary vascular development; 2) pulmonary vascular disease accompanying fetal development and perinatal life; 3) properties of pulmonary vascular endothelial cells; 4) role of bone marrow cells in pulmonary vascular disease; 5) insights into pulmonary thromboembolic disease; 6) role of pathology in the assessment of pulmonary vascular disease; and 7) considerations of tissue banking for research in pulmonary hypertension. These important goals provide a blueprint for future research that may significantly impact our present and future understanding of pulmonary hypertension.