RESUMEN
OBJECTIVE: This study aimed at a psychometric analysis of the Facilitative Interpersonal Skills (FIS) performance test, a test of therapist relational skills that has repeatedly been found to predict psychotherapy outcome. We investigated the reliability, unidimensionality, and convergent validity of a German language version and psychometrics relevant for repeated and short assessments. METHOD: Thirty-nine trainee therapists took the FIS performance test and responded to self-report scales. RESULTS: Inter-rater agreement and internal consistency were high. The findings suggest that the FIS is a unidimensional scale. Correlations between the FIS and self-reported social skills, interpersonal problems, and working involvement were absent to low. FIS performance was independent from specific video stimuli and there was no indication of temporal effects. CONCLUSIONS: The findings suggest that the FIS is robust and ready to be used in repeated assessments and in short form. Further conceptual clarification of the FIS is needed.