The current study examined predictors of outcomes across two school clinician-delivered treatments (i.e., treatment as usual [TAU] or modular cognitive-behavioral therapy [M-CBT]) for youth with anxiety disorders. Predictors reflected two broad domains—therapist factors (i.e., education, years of experience, therapeutic orientation, work related stressors/barriers, self-efficacy, and attitudes towards evidence-based practices) and treatment-related factors (i.e., dosage, child compliance with treatment, therapeutic alliance, therapeutic nonspecifics, and proportion and quality of evidence-based structure elements). One hundred and ninety-five youth (mean age 10.98; 50.3% female, 53.5% non-Hispanic Caucasian) and 54 therapists (90.7% female, 72.2% non-Hispanic Caucasian) that were enrolled and randomized in a previous study (Ginsburg et al., 2020) participated. Results showed that incorporation of more evidence-based structure elements (e.g., agenda setting, assigning homework) and higher child compliance with treatment significantly increased odds of response to treatment. These findings provide important information about key ingredients to successful treatments, regardless of treatment condition/modality, and can be used to inform future training and implementation of school-based treatments for youth with anxiety disorders.