The study aims to examine the latent structure of secondary traumatic stress (STS), its precursors, and the psychological effects of it on the population of service providers working with refugees passing through the Balkan route. A total of 270 service providers (57% female) of different professional backgrounds working directly with refugees took part in the study. Participants were assessed for STS using the Secondary Traumatic Stress Scale, the extent of secondary exposure to trauma (i.e., clients' traumatic experiences from the countries of origin and travel that were communicated to them directly), depression, anxiety, and quality of life. Comparisons of several confirmatory factor analyses following prominent PTSD conceptualizations showed that the model with three relatively distinct but highly correlated factors-intrusion, avoidance, and the blend of negative alterations in cognitions, mood, and reactivity (NACMR), had the best fit. STS has been shown to be positively correlated both with the amount of different traumatic experiences that were communicated to them as well as with the specific content of those experiences. Path analysis showed that the amount of secondary exposure to the clients' traumatic experiences during travel, but not in the country of origin, had exclusive relationships with all three factors of STS. NACMR demonstrated direct effects on anxiety and depression symptoms, while intrusions exhibited a direct effect on anxiety-related symptomatology only. The avoidance factor did not have any independent direct effects on anxiety or depression. Finally, the effects of STS factors on quality of life were fully mediated by an increase of depression-related symptomatology. Results provide evidence on the latent structure of the STS which partially deviates from the prominent models of PTSD thus questioning the isomorphism of two constructs on the empirical level. Additionally, findings provide insights on the cascade of events that make professionals working with traumatized people especially vulnerable to STS and broader psychological distress.