This paper explores the ways in which student health professionals undergo a transformation in their sense of identity as they engage with caring discourses that underpin healthcare. I argue that caring is a "threshold concept" by virtue of the "troublesome knowledge" with which students are confronted on meeting patients in practice. When superimposed on commonsense understandings of caring, medical connotations of care and moral and ethical dilemmas challenge students to develop their own personal framework within which to operate. I suggest a number of ways in which students can be helped to move forward towards or through the threshold to a more cogent understanding of caring. Subsequent positioning in terms of caring discourses forms a facet of the students' developing identities as healthcare professionals and therefore is a fundamental aspect of professional socialization.