Graduate students in mental health service training programs are at risk of experiencing burnout. Using adult attachment theory as the guiding framework, this study examined a conceptual model which depicted the direct and indirect effect of attachment insecurity on burnout and the subsequent psychological distress via low self-compassion and emotion regulation difficulty with two cultural samples recruited from the U.S. and Taiwan, respectively. The final sample included 216 U.S. mental health graduate trainees and 201 Taiwanese trainees. Structural equation modeling was used to analyze the data. Findings from the final models best supported by the data revealed that in both cultural groups, attachment anxiety contributed to lower self-compassion which subsequently resulted in greater burnout and that emotion regulation did not play a mediational role in the models. Results also demonstrated cultural differences in several paths of the research model. For the U.S. sample, only higher attachment anxiety indirectly contributed to more psychological distress through low self-compassion and burnout was best positioned as an outcome variable similar to psychological distress, instead of being a mediator. For the Taiwanese sample, on the other hand, both attachment anxiety and attachment avoidance demonstrated significant indirect effects on higher psychological distress through lower self-compassion and burnout was a 2nd tired mediator through which attachment anxiety indirectly contributed to higher psychological distress. These findings advanced our understanding of the role of adult attachment insecurity in the development of burnout and psychological distress for graduate trainees in mental health fields, as well as the possible cultural differences in the observed variables and their relations. Counseling implications, limitations, and future research directions were discussed.