Objective We describe the development and initial psychometric properties of the observer‐rated Global Therapist Competence Scale for Youth Psychosocial Treatment (G‐COMP) in the context of cognitive‐behavioral treatment (CBT) for youth anxiety disorders. Method Independent coders rated 744 sessions from a sample of 68 youth (mean age = 10.56 years) using the G‐COMP and the instruments of alliance, involvement, CBT adherence, CBT competence. Results Inter‐rater reliability coefficients, ICC(2,2), were greater than .60 for the 5 G‐COMP domain scores. G‐COMP scores yielded small to medium correlations with instruments of alliance (rs = .17–.44) and youth involvement in treatment (rs = .08–.53), and medium to large correlations with instruments of CBT competence and adherence (rs = .26–.63). Therapists in the research setting were rated higher compared to newly trained therapists in community clinics. Conclusion Preliminary reliability and validity of the G‐COMP are promising, but future research is needed with non‐CBT samples.