The pulmonary vasculature is frequently implicated in the pathophysiology of acute respiratory distress syndrome (ARDS). In recent years, we have also learned about the contributions it makes to the prognosis of acute COVID-19-associated ARDS. Further, post-COVID syndrome or post-acute sequelae of COVID-19 demonstrates the lasting effects that can remain from acute SARS-CoV-2 infection several months to years post-acute infection. There is evidence to suggest that pulmonary vascular dysfunction also plays a role here as well. In this chapter, we explore the contributions of pulmonary vasculature in ARDS, acute COVID-19-associated lung injury/ARDS, and post-COVID syndromes.