This study examined the processes of credibility monitoring used by secondary science and social studies teachers when conducting an online inquiry and examining websites and their perspectives on teaching these processes to students through verbal protocol analysis and semi-structured interviews. Eight educators, four science teachers and four social studies teachers, participated in this concurrent think-aloud study. Results indicated that, when conducting an online inquiry, middle school educators activated prior knowledge and selected sources based on credibility and relevancy. Social studies educators utilized lateral and vertical reading to assess an author's credibility, while science educators read through abstracts in order to determine an article's relevancy. Both groups recommended modeling and scaffolding instruction. When teaching students, social studies educators indicated it was important to emphasize that site presentation and structure impact credibility and relevancy. Science educators indicated it was important to emphasize evaluating and utilizing quality references and sources. Implications for research and professional development design for these findings are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]