Purpose: This study examined the measurement invariance of the Secondary Traumatic Stress Scale (STSS) across racial and gender groups among public child welfare workers. Method: Survey data from 2,004 participants were analyzed using a series of exploratory and confirmatory factor analyses to examine the measurement invariance of a 17-item scale assessing intrusion, avoidance, and arousal symptoms of secondary traumatic stress (STS). Results: The study identified a single-factor model that combined all STS symptoms. A measurement invariance test revealed that the STS scale did not achieve acceptable measurement invariance between White and Black workers. For gender, partial scalar invariance was supported although the latent mean of STS did not differ significantly between male and female workers. Conclusions: Findings underscore the importance of further research to improve the STS scale to better capture racial disparities in STS and reflect culturally specific symptoms of STS, especially among Black social workers.