This study examined the role of comorbid anxiety in treatment outcome for children with mood disorders (N = 165; age 8-11) participating in Multi-Family Psychoeducational Psychotherapy (MF-PEP). Assessments occurred at baseline, 6, 12, and 18 months for two randomly assigned groups: immediate treatment and 1-year wait-list. Most children (69%) had comorbid anxiety disorders. Baseline comorbid anxiety, as reported on the Children's Interview for Psychiatric Syndromes (ChIPS), was associated with higher Children's Depression Rating Scale- Revised (CDRS-R) scores but not Young Mania Rating Scale (YMRS) scores. Higher levels of anxiety symptoms were associated with lower Children's Global Assessment Scale (C-GAS) scores. Participation in MF-PEP did not significantly reduce anxiety symptoms (p = 0.62). However, presence of comorbid anxiety did not impede reduction in depressive (CDRS-R, p = 0.74) or manic (YMRS scores, p = 0.94) symptoms following MF-PEP. More baseline anxiety symptoms were associated with greater improvement in C-GAS scores post-treatment (p = 0.02). Implications are discussed.