This study investigated pre-service teachers' epistemic beliefs about the Internet using the Inventory of Internet-Based Epistemic Beliefs (IBEB). Also examined were their belief profiles to delineate the effect of IBEB on pre-service teachers' engagement in online reading activities and intention for ICT integration for constructivist learning activities. Participants were 474 teacher education students in Taiwan. Results revealed the four hypothesised constructs -- structure, uncertainty, source, and justification for Internet knowledge -- with good validity and reliability. Four epistemic belief groups were derived based on these constructs; and they exhibited differential effects on the validating variables. Cluster 1 was characterised by four positive epistemic beliefs (the "positive beliefs"), Cluster 2 by four negative epistemic beliefs (the "negative beliefs"), Cluster 3 by modest scores of the epistemic beliefs (the "modest beliefs"), and Cluster 4 by positive uncertainty and justification scores as well as negative structure and source scores (the "high justification" and "uncertainty"). Findings suggest that intervention targeting pre-service teachers in the "negative beliefs" and the "modest beliefs" may be necessary to foster positive epistemic beliefs for better constructivist learning in the online environment.