Through detailed interrogation of the molecular pathways that contribute to the development of pulmonary arterial hypertension (PAH), the separate but related processes of oxidative stress and cellular metabolic dysfunction have emerged as being critical pathogenic mechanisms that are as yet relatively untargeted therapeutically. In this review, we have attempted to summarize some of the important existing studies, to point out areas of overlap between oxidative stress and metabolic dysfunction, and to do so under the unifying heading of redox biology. We discuss the importance of precision in assessing oxidant signaling versus oxidant injury and why this distinction matters. We endeavor to advance the discussion of carbon-substrate metabolism beyond a focus on glucose and its fate in the cell to encompass other carbon substrates and some of the murkiness surrounding our understanding of how they are handled in different cell types. Finally, we try to bring these ideas together at the level of the mitochondrion and to point out some additional points of possible cognitive dissonance that warrant further experimental probing. The body of beautiful science regarding the molecular and cellular details of redox biology in PAH points to a future that includes clinically useful therapies that target these pathways. To fully realize the potential of these future interventions, we hope that some of the issues raised in this review can be addressed proactively.