Calling for major reform in medical education, the Carnegie Institute report 'Educating Physicians' espoused the importance of assisting student trainees in forming their professional identities. Here, we consider the question: At what educational stage should future physicians begin this process? The literature suggests that the process begins when students matriculate in medical school; we posit, however, that premedical students can begin their proto-professional development as college undergraduates. We describe here the pedagogy of Cornell University's urban semester program (USP), which enables college students to participate in shadowing experiences as part of an integrated structured study programme. USP students report improved communicative competency, changes in their perceptions and attitudes toward medical practice, and powerful influences on their personal and professional development upon completion of the programme. We suggest the solution to the question of 'When and under what conditions should shadowing take place?' is to utilize a structure that combines the exposure of college students to the professional environment with a didactic and self-reflective curriculum, thereby supporting students in their early professional development. We conclude that educational efforts aimed at developing professional identity and behaviour can begin before students enter medical school.