Knowledge Building is a socio-constructivist approach that aims to engage students in a knowledge-creation environment as early as possible to get them ready for the knowledge society. Rather than following fixed procedures or scripts, the twelve Knowledge Building Principles, such as "collective responsibility," "real ideas and authentic problems," and "improvable ideas," have framed the Knowledge Building approach. These principles support teachers and students to identify and work on their needs to improve the coherence and explanatory power of their community knowledge. We hypothesize that the extent to which students adopt these principles influence their group Knowledge Building. We analyzed the online discourse, design artifacts, and reflection of 39 pre-service teachers. We found that the participants did well in contributing diverse ideas, engaging in Knowledge Building discourse, taking initiatives in their groups, and considering each other as legitimate contributors. However, they needed support to use authoritative sources, assess their discourse and knowledge status, rise above diverse ideas to achieve new syntheses, and make complementary contributions across teams. Principles such as "improvable ideas," "embedded and transformative assessment," "democratizing knowledge" and "symmetric knowledge advancement" tend to distinguish the high-performance groups from the medium- and low-performance groups. This study implies the importance of teachers and researchers to help students engage in productive Knowledge Building using the twelve Knowledge Building Principles.