Despite recent efforts to rehabilitate Dewey's ontology, little notice has been given to how Dewey's process ontology bears on his social and political diagnosis in The Public and Its Problem. While the diagnosis focuses on the public as those who are harmfully affected by indirect consequences of actions and transactions, process ontology qualifies the uncertainty of action consequences, as well as the harmful nature of such consequences, in the light of ontological dependencies of human action on non-humans, artifactual and natural. Dewey's ontological analysis of human communication brings out various such dependencies by considering communication as a material as well as a symbolic medium for social coordination of action and for instituting social uses of tools and technologies, and by viewing human communication as biologically continuous with the behavior of non-human sentient organisms. Process ontology further considers human agents' needs as biologically conditioned and as socially and economically dependent through habitual accommodations to markets. Through such analysis of human agents as organic sentient beings and as vulnerable and dependent consumers, process ontology qualifies harmful consequences that affect publics. Finally, Dewey's process ontology brings out the ecological relevance of his social and political diagnosis: the uses of science and technology that enable economic activities in industrial societies systematically neglect biological interdependencies and put life conditions of human as well as non-human organisms in jeopardy.