Overall, the United States’ population is becoming more diverse, and children in minority groups have many disadvantages due to circumstances beyond their control. They experience more poverty (US Census Bureau, 2017), unequal educational opportunities (US Census Bureau, 2019), discriminatory practices (Pascoe & Smart Richman, 2009), trauma (Sacks & Murphey, 2018), mental health diagnoses, and inadequate mental health services. Mental health professionals who work with children, specifically play therapists, are called to be more responsive to the increase in diversity of the growing population of children. To support diverse children and support therapists in offering responsive services and advocate on behalf of children, researchers need to explore factors that may influence their social justice advocacy attitudes. Therefore, a standard multiple regression was utilized to examine the impact of play therapists’ (N=409) adverse childhood experiences, attitudes related to trauma-informed care, and cultural humility with regard to their social justice advocacy attitudes. Results indicated that attitudes related to trauma-informed care and cultural humility contributed significantly to the prediction of social justice advocacy attitudes, accounting for 11% of the variance. Implications, limitations, and recommendations for future research are discussed.