This case study examines the complex relationship between beliefs, practice, and change related to inquiry-based instruction of one science teacher teaching in a high-poverty urban school. This study explores how video-supported collaboration with peers can provide the catalyst for change. Transcribed collaborative dialogue sessions, written self-reflections, and videotapes of lessons were used to identify and isolate the belief systems that were critical to the teacher's decision making. The Interconnected Model of Professional Growth was then used to trace the trajectories of change of the individual belief systems. Analysis of the data revealed the relationship between beliefs and practices was complex in which initially espoused beliefs were often inconsistent with enacted practice and some beliefs emerged as more salient than others for influencing practice. Furthermore, this research indicates change in both beliefs and practice was an interactive process mediated by collaborative and self-reflection through participation in the video-supported process.