The purposes of this research are to understand and describe the core competence for domestic and sexual violence counseling on interdisciplinary system scollaboration. Qualitative research method is adopted. The researchers conducted in-depth interviewsand administered a questionnaire. The 10 participants in the research are from different counseling clinics in Taiwan. The major findings were: (1) Three core competencies for domestic and sexual violence counselingin interdisciplinary systems includedcompetenceincounseling explainationand evaluation of collaborative effect, competence in identifying key resources and interdisciplinary systems’ professional languages, and competence inapplying ecological systems theory and group dynamics to serve as change agents. (2) Three collaboration patterns for domestic and sexual violence counselingin interdisciplinary systems included: one system initiates positive input and facilitates interactions, respondingsystems weaken feedback and terminate interactions, and one system gives input but receives no feedback from the other systems.Suggestions are offered for community counseling psychologists, educators, and supervisors of counselor training, interdisciplinary systems, and further research.