Situated within an informal learning context, this study examines how a group of pre-service teachers in Hong Kong use Facebook and Google Sites on their own initiative to fulfil their academic and socio-emotional needs during their teaching practice. Also included in the study are the motivating and inhibiting factors that influence student online participation. Guided by an informal learning model and the literature relating to online participation and sense of community, this exploratory study generates its findings from questionnaires, individual interviews and online postings. The results show that the Google Sites created an avenue for the students to share a range of self-developed teaching resources and ideas. Facebook is a more interactive platform through which the participants seek peer support, exchange teaching ideas, and engage in discussions on a variety of topics. Structure and control provided by Google Sites and immediacy and interactivity afforded by Facebook become complementary to each other.