Social studies teachers in the United States are often unprepared or hesitant to teach about race and racism. This is especially true among White teachers. If teachers are to teach American history, they must be prepared to teach about race and racism, starting with the construction of race in Colonial America and continuing to emphasize the prevalence of racism throughout American history and today. This dissertation was a critical participatory action research study of two White teachers who tried to improve their teaching about race, racism, and slavery in Colonial America in the context of a White Jewish private middle school. The study asked how the teachers collaborated, how their unit changed over two years, and how student responses changed. Data were collected through interviews with teachers and students, during recorded teacher planning meetings, through classroom observations, and by collecting classroom artifacts. Qualitative analysis through the lens of Critical Race Theory led to a few major findings. The teachers collaborated through a spiraling process of reflection, learning, pooling information, drafting new plans, and iterating on the unit. Their working relationship was characterized by their complementary skill sets and trust in each other's critiques and work. The unit changed to include more about the resistance of enslaved people and the construction and institutionalization of racism in early America. They also learned to create a classroom environment that was more trusting, supported more productive discussion about race and racism, and dealt more effectively with challenging comments about race. Student responses also changed. In Year 2, students recalled more examples of resistance, more strongly emphasized the importance of understanding institutional racism, and utilized prior knowledge about antisemitism to discuss racism more productively. These findings led to recommendations about teaching about race and racism, teacher learning, and future research. [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.]