The early years of teaching are important for science teachers, but little is known about how science teachers develop professionally in their early years. This mixed methods study took a longitudinal view of the early years of teaching. Following 95 secondary science teachers over a 5-year period, this study examined the beliefs, pedagogical content knowledge (PCK), and practices of the teachers during and after their induction programming. It drew upon the conceptual framework of opportunities to learn to contemplate the experiences of the teachers in relationship to their beliefs, PCK, and practices. Interviews and observations comprised the data in the study, which were analyzed quantitatively and qualitatively and then integrated to understand the teachers' development. The quantitative analysis revealed that the early career teachers experienced no significant change in their beliefs over time but did experience significant change in their PCK and in some of their instructional practices. The qualitative analysis highlighted the difficulty in changing the instruction of the teachers, administrative decisions that constrained or contributed to the learning of the new teachers, and the different professional learning opportunities new teachers drew upon over time. These results suggest that early professional development experiences provided some support for the newly hired teachers, but not enough to challenge their beliefs or establish the instructional repertoires envisioned in the science education reforms. To better support the development of early career science teachers, they need strategic learning opportunities over time that involve administrators, colleagues, and science teacher educators.