In response to an increased emphasis on disciplinary literacy in the secondary science classroom, an investigation of the literacy processes utilized by high school students while reading scientific text was undertaken. A think-aloud protocol was implemented to collect data on the processes students used when not prompted while reading a magazine article and a selection from a textbook. Following the think-aloud, participants provided an oral summary that was analyzed for content and quality to assess the effectiveness of the strategies. The data showed that familiarity with text structure and prior knowledge of the content affected the processes utilized. Differences between groups (frustration, instructional, and independent levels) were noted in reading both texts. Overall, participants made references to graphics but did not rely on the content of the graphics for clarification purposes. Group differences included the amount of attention given to content vocabulary; independent level readers spent more time previewing and reviewing vocabulary. Summary scores indicated that instructional level participants used processes most effectively. Frustration level readers demonstrated the ability to utilize a variety of processes through one-time use. Findings suggested: 1) increasing instruction on interpretation of graphics; 2) providing students with varied forms of scientific text; 3) focus on teaching strategies to frustration level readers; 4) encouraging summarization activities in the classroom; and 5) using multiple forms of assessment to identify disciplinary literacy processes. [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.]