This study explored the use of wikis in a science inquiry-based project conducted with Primary 6 students (aged 11-12). It used an online wiki-based platform called PBworks and addressed the following research questions: (1) What are students' attitudes toward learning with wikis? (2) What are students' interactions in online group collaboration with wikis? (3) What have students learned with wikis in a science inquiry-based project in a primary school context? Analyses of the quantitative and qualitative data showed that with respect to the first research question, the students held positive attitudes toward the platform at the end of the study. With respect to the second research question, the students actively engaged in various forms of learning-related interactions using the platform that extended to more meaningful offline interactions. With respect to the third research question, the students developed Internet search skills, collaborative problem solving competencies, and critical inquiry abilities. It is concluded that a well-planned wiki-based learning experience, framed within an inquiry project-based approach facilitated by students' online collaborative knowledge construction, is conducive to the learning and teaching of science inquiry-based projects in primary school.