Scientific argumentation is a core scientific practice. Although scientific argumentation has been linked to increased learning of scientific content, improved reading, writing, and critical thinking, traditional science classrooms have not included scientific argumentation. Teachers often have little experience learning or teaching science through argumentation and need support to integrate this complex practice of science into their classrooms. This study compared four high school biology teachers' instruction of scientific argumentation as they worked with a literacy coach. Data were collected through interviews, audio recordings of classroom instruction and literacy coaching sessions, and artifacts. After analyzing the data, several key findings stood out from this study. First, all of the teachers incorporated instruction that research has identified as supportive of student learning of scientific argumentation. Second, the teachers' learning goals or purposes for scientific argumentation informed the decisions they made as they incorporated scientific argumentation. Third, teacher experiences were especially important in teachers' instructional decisions when their beliefs and experiences were contradictory. Finally, all teachers, regardless of the amount of argumentation instruction they incorporated into their classroom developed better understandings of scientific argumentation and best practices to support student learning. [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.]