For the past decade, as concerns over the quality of California schools have risen, state policymakers have sought ways to strengthen the state's teacher workforce. In the face of teacher shortages, numerous policy efforts have focused on preparing, recruiting, and retaining fully qualified teachers. The results of these policies have been significant; however, a number of sobering trends remain: poor students are still more likely to get an under-prepared teacher; at the secondary level, where enrollment is rising, many teachers are assigned "out-of-field" to classes for which they have minimal or no preparation; and nearly a quarter of new teachers enter the workforce without having earned the state's preliminary credential. These facts, combined with the increasing age of the teacher workforce and a drop in credential production, underscore that policymakers need to continue to focus on ensuring that all students have a fully qualified teacher. Additionally, looking across the teacher development continuum, weaknesses are apparent in how teaching quality is measured and how that information is used to support teachers. California needs to create a teacher development system designed to strengthen teaching quality. The system should link the components of the teacher development continuum, be based on a common definition of teaching quality, promote reliable measures of teacher knowledge and skills, and support the development of high-quality teaching. A system of teacher development can continuously improve teaching quality and ultimately result in improved student outcomes. Four primary recommendations are made to strengthen California's teaching force: (1) Review and align the current components of teacher development to form a system focused on strengthening teaching quality; (2) Continue to develop the California Longitudinal Teacher Integrated Data Education System (CALTIDES) and use the data derived from the system to inform decisions about the ways in which the components of teacher development can be revised, aligned, and made into a system that learns, adapts, and evolves; (3) Regularly assess classroom practice and use the information gathered to strengthen teaching quality; and (4) Encourage policies that will build and support a larger pool of prospective teachers. Appended are: (A) Research Methods; (B) Additional Supply, Demand and Distribution Graphs; (C) Teacher Preparation Measures; and (D) Source and Technical Information. (Contains 57 exhibits.)