The population in the United States is becoming more racially diverse. Young children in minoritized groups have many disadvantages due to circumstances beyond their control. They experience more poverty (US Census Bureau [USCB], 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, must be more responsive to the needs of these young children through both clinical works and social justice advocacy. To support racially diverse children, to support therapists in offering services, and to advocate on behalf of children, researchers need to explore factors that may influence their social justice advocacy attitudes. The purpose of this study was to examine how adverse childhood experiences, attitudes related to trauma-informed care, and cultural humility were related to social justice advocacy attitudes among play therapists. A standard multiple regression was utilized (N = 409). 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.