Using the Gap Analysis problem-solving framework (Clark & Estes, 2008), this project examined collaboration around student achievement in the Pasadena Unified School District (PUSD) from the teacher perspective. As part of a tri-level study, two other projects examined collaboration around student achievement in PUSD from the perspectives of central office administrators (Llamas, 2013) and school site administrators (Salinas, 2013). The primary purpose of the current project was to identify the root causes in knowledge and skills, motivation, and organizational factors that explain the gap between PUSD teachers' current performance and that required to achieve PUSD's organizational goal to institutionalize collaboration around student achievement. Mixed methods were used to collect quantitative data from 219 teacher surveys and qualitative data from four teacher interviews. These data were used to validate and prioritize assumed causes in knowledge and skills, motivation, and organizational factors. The findings revealed root causes related to the following: 1. Organizational support for effective collaboration around student achievement; 2. Teacher commitment to professional learning; 3. Teacher capacity related to curriculum and assessment. Proposed solutions were aimed at strengthening organizational supports, fostering teacher commitment, and creating a framework for capacity building. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]