This article evaluates Wittgenstein’s possible contributions to an epistemology of psychology. Although the author admittedly neither proposes an epistemology nor examines specific issues of psychology as a science, we understand that his reflections on the meaning of psychological concepts may contribute to a better understanding of psychology as a science, which involves understanding its object and methods. With that goal in mind and based on the concept of language developed in his second phase, especially in his work Philosophical Investigations, we retrace his efforts to obtain a picture of the grammar of psychological concepts, emphasizing two of its aspects: first, the place and role of first‑person expressive propositions in the psychological language-game and second, how this understanding of the perspective of the first person implies in refusing to reduce explanations of human behavior to causal explanations in favor of explanations based on reasons.