The aim of the thesis was to provide a deepened understanding of upper secondary school teachers’ information seeking for teaching material on the Internet. The research questions were: In what ways do upper secondary school teachers in Swedish and History search for teaching material on the Internet? How do upper secondary school teachers in Swedish and History make judgments of relevance of teaching material found through the Internet? A sociocultural perspective was set as the theoretical framework and five semi-structured interviews were conducted. All participants had worked several years as teachers. Concepts from two information seeking models were used in creating a tool for analyzing the data. As were the concept cognitive authority and the two cognitive criteria reliability and usability. The analysis showed that the ways my participants search for information and the judgements of relevance they made to a large extent were tied to their many years of teaching experience. Their information practices therefore differed from those found in earlier research on teacher candidates and teachers who had recently entered the profession. The analysis also showed that my participants felt comfortable in their role as cognitive authorities; that the different teaching communities to which they belonged affected their information seeking; and that they had an awareness of how they used different information practices in different contexts.