Context: Policymakers have increasingly advocated for incentive-based approaches for improving urban schools. Purpose of the study: Few studies have examined the implementation of incentive based approaches in the urban charter school context. This paper presents research findings from a 4-year longitudinal study of the implementation of a comprehensive incentive-based program for school improvement. Setting: The study was conducted in a cluster of 12 charter schools in a large urban school district. Participants/Subjects: Participants in the study included classroom teachers, administrators, and staff in the charter schools; program staff from the school district; and consultants to the project. Research Design: The study used a mixed methods design, which included a comparative case study, and quasi-experimental design. Data Collection and Analysis: Qualitative data elements included semi-structured interviews and observations of program activities. Quantitative data elements included the official classroom teaching evaluation scores, teacher attitudes survey data, standardized student achievement scores from state and district assessment programs, and researcher-developed surveys of teacher and administrator perceptions. Results: The results suggest that, in addition to questions about the viability of this comprehensive incentive model, there were several challenges related specifically to the context of the schools that affected program implementation. These included: misconceptions about performance pay; difficulties learning, understanding and sustaining a complex professional development model; poor fidelity of program implementation; varying capacities of the leadership teams; inability to sustain the incentive component; differences in the contexts and missions of the participating schools; and high teacher turnover at the schools. All the 12 schools reported some improvement in student achievement which led to performance rewards; however, this was not substantial or consistent over the course of the 4 years of implementation. The program also did not impact teacher retention at the schools. Schools that benefited the most from the program demonstrated an alignment of goals between the program staff, school leadership, and teachers. Conclusions/Recommendations: The study findings suggest that even comprehensive incentive-based models are not yet viable and have limited effectiveness. Educators needed significant salary increases to be incentivized by money and incentive-based models need to be simpler in design for participants to understand them. The aspect that was somewhat sustained was the professional development and collegiality among the teachers indicating that a professional community is what teachers appreciated most from the program.