The CAREERS study brings together researchers from education, psychology and the sciences and scholar-practitioners to examine the factors that, once understood, can be addressed in the preparation of both pre-service and in-service teachers to guide elementary children in exploratory and inquiry-based science lessons. The overarching goal is to develop models that describe the interconnections among key constructs in order to reexamine the content of elementary science methods courses, mentoring for early career teachers, and professional development opportunities and coaching for teachers all along the Teacher Professional Continuum. The main constructs of interest in this five-year study are beliefs about science teaching, science content knowledge, readiness to change teaching practice, teachers' sense of efficacy in teaching inquiry-based science and transfer and fidelity to elements of professional development. CAREERS is examining these beliefs, attitudes and knowledge for 300 pre-service teachers and 500 mid-career teachers. Additionally, science teaching practice is being examined for all 300 pre-service teachers during the science methods course with a follow-up on 60 of these teachers through student teaching and 30 through their first two induction years. The science teaching practice of the 60 mid-career cooperating teachers who supervise these student teachers is also being studied. The study design provides a longitudinal view of teacher development that examines teaching effectiveness at critical transition points (i.e., from science methods through student teaching and to induction) and how eight hypothesized factors influence fidelity to methods taught in an inquiry-based methods course. A randomized study examines the influence of characteristics of cooperating teacher mentors (their degree of experience with inquiry based instructions) on continued success on the student teachers in maintaining their inquiry approach to teaching.