For the past two decades, the mathematical achievement of American students has been a major concern. Students in traditionally marginalized communities often are affected more and perform less proficient in mathematics due to issues related to teacher effectiveness. One approach to increase teacher effectiveness has been through collaboration. The purpose of this study was to explore the structural and cultural conditions that support high performing collaboration in mathematics. This study not only investigated the supporting structural and cultural conditions that have been identified in the extant literature but it also examined the interaction between these conditions in two high performing cases. The study also provided an opportunity to examine teachers' perception of collaboration and its influence on their teaching. The investigation relied on the frameworks of the structural conditions including duration, coherence, content, active learning, and collective participation and two cultural conditions of teacher efficacy and trust. Using mixed method, the methodology of the study used surveys and interviews to identify the supportive conditions and the interactions between these conditions in two instructive cases of collaboration. The findings revealed six structural themes of time as an important condition of collaboration, focus on teachers' daily classroom goals, focus on teachers' content knowledge, teacher learning through collaboration and participation of teachers of the same grade level. The findings also pointed to high level of collective efficacy and trust as supportive cultural conditions. The significant finding of this study was the new theoretical model, Interdependence Model. This new model includes one additional structural condition of physical proximity, and two additional cultural conditions of focus on students' best interest and culture of high expectation. This new model reflects intense interconnection and interdependence between the structural conditions, cultural conditions. This model shows that the cultural conditions lay the foundation for the development of the structural conditions. More importantly, the Interdependence Model presents that trust is the most critical predictor for the development of the structural conditions. It is hoped that the new theoretical model, which originated from a strengths-based approach, will reinforce the conditions that exemplify high-performing collaboration in schools