This study examined the effectiveness of teletherapy compared with face-to-face psychotherapy in routine community practice. It also explored whether therapeutic alliance was associated with treatment outcome across delivery formats and examined therapist effects across modalities. Data were drawn from a large naturalistic routine outcome monitoring database representing treatment as usual across 86 community-based clinics in the United States. The sample comprised adults (n = 58,141) treated by (n = 1,552) therapists and youth (n = 20,985) treated by (n = 1,224) therapists. Cases were included if treatment began between January 1, 2018, and December 31, 2025, intake scores were within the clinical range, and at least two assessments were completed. Episodes were classified as 100% face-to-face, 100% video-based teletherapy, or mixed delivery. General linear models examined associations between alliance variables and outcome, and therapist effects were estimated separately using PROC MIXED. Across both adult and youth samples, mixed delivery was associated with better outcomes and a greater mean number of sessions than either face-to-face or teletherapy alone. Alliance scores were associated with treatment outcome, particularly when the alliance improved over the course of therapy, although alliance ratings did not differ meaningfully across delivery formats. Therapist effects accounted for 5.3% of variance in outcome overall, with 3.2% for adults and 7.8% for youth. For adults, therapist effects were similar across video and face-to-face therapy, whereas for youth they were higher in video therapy (11.2%) than in face-to-face therapy (8.05%). Teletherapy appears to be a clinically useful alternative to face-to-face psychotherapy, particularly when combined with in-person sessions. A mixed model of care may improve accessibility, increase treatment engagement, and enhance outcomes in routine community settings.