The study aimed at investigating how different young people going through the post-high school transition set, monitor, pursue, and renegotiate career goals in real-time and in everyday life circumstances. A theoretically driven proposition supported the conceptualization of career goals as complex dynamic systems and guided the examination and description of the moment-to-moment processes shaping the (re)construction of career goals. The study adopted an exploratory research approach and was based on a longitudinal case study design. Diary reports were collected for 39 weeks. Participants were four young people (three females, one male) who at the onset of the study were 18 years of age and attended their last year of high school. A ground-up analysis of the data was conducted, which culminated in a comprehensive narrative describing and interpreting the properties and behavior of the participants’ career goal system. Results showed that despite some similarities in how the career goal system of each participant reacted to challenging events, these systems operated in a highly idiosyncratic manner. Differences in the real-time properties and behavior of the career goal systems provided insights into the mechanisms driving macroscopic processes of career goal construction and highlighted their relevance for young people’s identity formation.