I conducted a two-year case study of a cohort of two middle school mainstream teachers, one a mathematics and science teacher and the other a language arts teacher, and one elementary teacher involved in the LSciMAct ("Transforming Literacy, Math and Science Through Participatory Action Research") professional development project. The teachers and I conducted action research using videotaped classroom practices to discuss classroom discourse. Using a sociocultural/CHAT theoretical framework, I drew on literacy, discourse analysis, and professional development research. In examining how teachers used discourse analysis as a tool for conducting action research, I used ethnographic methods and an iterative process of recording study group meetings, classroom observations, and focus groups. In addition, I collected written participant artifacts, such as teachers' fieldnotes, coding, and transcripts of classroom interactions. Teachers used discourse analysis as a mediational tool to study their classroom data. The goal of the activity system was for teachers to use these tools to study their practices and design curriculum integrating literacy, math, and science. One finding was that the teachers developed the majority of their awareness(s) using the transcripts and other analytic tools outside of the elementary/middle school context. Thus, conducting long-term PD required fostering what I named "ethnographic relationships," or relationships that considered and honored diverging and converging researcher and participant perspectives, experiences, and goals. Another finding was that the teachers redeveloped the analytical tools to transform their practices. One of the most challenging concepts in the PD was "third space." In order to move beyond the tension they experienced, the teachers attempted to work in a negotiated space, or third space, where the expertise of students and teacher were fluid and informed one another. Thus, a third finding was that instructional moment-to-moment third spaces in class and the way activities were designed needed to work together to inform authentic curriculum development. The significance of this study is, first, it positioned teachers through collaborative professional development to take up a theoretical framework and develop curriculum and pedagogical practices and, second, it allowed them to analyze their efforts using the same framework as a tool for continued professional development. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]