Teachers with seven years of teaching experience or less (n = 10) participating in a large-scale mathematics professional development program in the United States were interviewed. The goal of this qualitative study was to better understand less experienced teachers' reactions to professional development and professional support in the teaching profession. The interview data indicate that these less experienced mathematics teachers are not satisfied with their mentors or collaboration in their department and would welcome opportunities for classroom observations. In addition, these teachers were disappointed and surprised at their more experienced peers' lack of mathematics content knowledge. The results of this study have direct implications for the structure and philosophy for professional development to better serve incoming and less experienced teachers. (Contains 1 table.)