The present study attempts to examine the effects of group awareness on knowledge construction and further surveys in what ways the different group awareness types support the collaboration in CSCL. In this quasi-experimental study, we adopted a self-developed group awareness tool that could display cognitive, social and behavioral group awareness in an authentic semester-long class with 93 undergraduates involved in. Using a mixed research method, we explored the effects of group awareness on knowledge construction by comparing the characteristics and behavioral patterns of knowledge construction between GA (with the GA tool) and NA (without the GA tool) classes and further examined the different role of three group awareness types in supporting collaboration through interviews. The content analysis indicated that GA groups centered their collaboration on negotiating meaning or constructing new knowledge (C3) and conducted more higher-level knowledge construction behaviors (C4 & C5) while in NA groups, sharing and comparing information (C1) appeared to be the most frequent behavior. The sequential analysis showed two distinctive sequential patterns, C4[right arrow]C5 and C5[right arrow]C4 in GA class and C2[right arrow]C4 in NA class. The interview revealed that students thought cognitive and social group awareness played a major role in supporting their collaboration while unexpectedly, the behavioral group awareness was of little use. Finally, pedagogical implications were suggested.