An investigation was conducted to study shared knowledge construction process in an Open-Source Software Development (OSSD) community. Using a qualitative study approach, we examined the resources, tools, and activities in the Gallery community to create a rich description of the interrelationships among people, activities, and media. of particular interest was how the individuals contributed to the building of a shared knowledge base through collaborative problem-solving and decision-making processes, mediated with the OSSD environment. The study indicated that the collaboration process was symbolized by multiple rounds of discussions, which were means to pool individuals' expertise and experiences to obtain quality problem-solving and decision-making outcomes. The study also revealed that the OSSD environment mediated the collaborative efforts through virtual collaboration space, visual organization, and communication tools. The findings have important implications for designing effective instruction specifically for computing disciplines in promoting students' collaborative problem solving and decision making.