In discussing the functions of education Gert Biesta distinguishes qualification, socialisation and subjectification. In subjectification higher education facilitates the evolution of students as distinctive self-determining persons. This paper foregrounds and discusses 'student self-formation', a paradigm of subjectification with fecund potentials for empirical inquiry. Self-formation emphasises reflexive agency, whereby students consciously monitor and develop themselves on an ongoing basis. The paper draws especially on Margaret Archer's discussion of reflexive agency. It argues that the core features of self-formation that are specific to higher education are engagement in disciplinary knowledge, and in activities and relations beyond the classroom that are part of student life. Student self-formation is both a norm to be achieved, with lifelong learning potentials, and a descriptor of existing practices. By its nature self-formation is never complete and its incidence is uneven among students, with some of them scarcely experiencing it. Conditions and potentials for reflexive self-formation vary on the basis of factors including the degree of immersion in higher education, the scope for agentic initiative, personal resources and support, institutional and pedagogic resources and arrangements, and existential challenges (e.g. transitions between countries and cultures) that can trigger accelerated self-reflection and transformation.