This study explored relationships between Internet-specific justification beliefs and source evaluation and corroboration during Web search. Fifty university students completed the Internet-Specific Epistemic Justification Inventory (ISEJ), which targeted beliefs concerning the justification of Internet-based knowledge claims about natural science issues. Two to five days later, they conducted a Web search in order to communicate a justified position regarding an unsettled and unfamiliar socio-scientific issue. Using think-aloud and trace methodologies, participants' source evaluation and corroboration behaviors were examined. Furthermore, the extent and relevance of their post-search written justifications for their recommendation about the controversial issue were analyzed. Results showed that beliefs in justification by authority positively predicted comments regarding source evaluation, the percentage of visited websites that were listed beyond the first three Google search results, and the likelihood of opening multiple browser tabs. Beliefs in personal justification negatively predicted comments regarding corroboration of information across websites and the number of relevant aspects included in the written justifications. Finally, participants with stronger beliefs in justification by multiple sources gave more extensive justifications for their recommendation and included more relevant aspects in those justifications.