This study examines the growth of an innovative pre-service science teachers' (PST) community over a period of three years in a voluntary and informal setting for teaching science to high school students. The objective of this study is to understand the traits and conditions necessary for the learning and development that occurred in the PST group. We describe the growth of the PST group with a focus on the group's endeavor to move from simple laboratory work to a more inquiry-based approach to science instruction. In doing so, we seek to articulate the growth of the group by focusing through the lens of cultural historical activity theory on how its meanings, tools, and priorities were constantly formulated and examined within the community.