We describe the impact of an African American history centred collaborative teacher study group (CTSG) professional development experience on the cultural competence of 20 secondary Social Studies and English Language Arts educators. Using mixed methods, baseline data indicated slight movement from the colourblind to the cultural pre-competence level for most. Race, as a fixed category, slightly impacted the increase in participants' cultural competence levels. Gender and teaching experience, however, had little if any impact on cultural competence levels. Selected interviews suggested that participants recognised the importance of teaching with diversity in mind. Yet, many acknowledge lacking the skillset to adequately meet the linguistic and cultural diversity of their students. Overall, participants noted that the professional development experience broadens their cultural competence awareness and would influence their instruction practice.