In this article I engage with Foucault’s reading of the Platonic dialogue Alcibiades in his Hermeneutics of the Subject, developing his view that this text offers a model of the self-constitution of the subject. Foucault’s reading is part of his larger aim to find alternative conceptualizations of subjectivity besides the Cartesian ones that he thinks have dominated modern thought. His reading has been contested; but I argue that the Alcibiades does indeed develop a notion of subjectivity as reflexive and self-constituting. Moreover, two aspects of the text that Foucault misrepresents make even clearer the distance of its notion of subjecthood from a Cartesian view. First, the reflexive subject of the Alcibiades, though viewed as essentially intellectual, is the result of an ascetic practice of self-constitution. Second, this practice is essentially interpersonal, operating through reciprocal and equal dialectic.