As part of a longitudinal study into identity development in upper-level physics students a phenomenographic research method is employed to assess the stages of identity development of a group of upper-level students. Three categories of description were discovered which indicate the three different stages of identity development for this group of students: Student, Aspiring Physicist, and Physicist. The stages of identity development were distinguishable by the variation in their career definitiveness, their metacognitive level, and their assessment of when has become a physicist.