The ability to reason about observed classroom situations constitutes an essential aspect of teachers' professional vision and is seen as a key element of initial teacher education. The three aspects of the ability are as follows: to describe, explain, and predict classroom situations. Research has shown that field experiences, the acquisition of theoretical knowledge on effective instruction, and learning with video supports preservice teachers' development in the three skills. However, the long-term effects taking into account intra-individual differences remain unexplored when it comes to tracking preservice teachers' changes within teacher education programs that combine all three components. In this study, we investigate whether intra-individual differences between preservice teachers' professional vision occur in an innovative teacher education program (integrating theory and practice), whether these differences result in different changes, and whether the attendance in the program leads to similar individual developments in preservice teachers' professional vision. Data of N = 64 pre-service teachers' reasoning skills were measured with the Observer Research Tool at four measurement points and analyzed using multilevel analysis. The results showed a linear growth in all three skills in the course of the program. Furthermore, preservice teachers systematically differ in their entry levels as well as change rates in professional vision.