William James's pragmatic theory of truth has been controversial ever since its publication, and is dismissed by some philosophers as seriously defected. This paper aims to do justice to it by means of elucidating James's view of the dynamical relation between opinions taken as true and what he calls ”threefold realities” in an individual's system of beliefs. The first part of this paper shows that his theory of truth aims not to give a new definition of ”truth,” but to clarify, from the broadly practical perspective of human activity, the meanings of ”agreement” and ”reality” in the definition that truth agrees with reality, which James accepts; that he holds that threefold realities can exert coercive influence on an individual's system of beliefs; and that the archetype of his theory of truth is his holistic view of how a new idea comes to be accepted in an individual's system of beliefs, which anticipates what is maintained in the last section of Quine's well-known ”Two Dogmas of Empiricism.” The second and last part of this paper pursues the task of clarifying, by applying the theses presented in the first part of this paper, five paragraphs quoted from his Pragmatism which are rather puzzling at first sight.