Motivation is associated with cognitive behavioral treatment (CBT) outcomes. We examined the factor structure of a motivation measure, and if motivation factors were differentially associated with CBT outcomes for children with anxiety. The sample comprised 179 children aged 8–15 years (M age = 11.5 years, SD = 2.1; 53.0% girls) with anxiety disorders who received CBT in a randomized controlled community clinic trial. Participants completed the Nijmegen Motivation List – child version (NML-C) at treatment onset. Outcomes were diagnostic recovery, anxiety/depression symptom and clinical severity change from pre-treatment to post-treatment, one-, and 3.9-years follow-up, and treatment dropout. Principal component analysis showed that the NML-C comprised two factors, preparedness (beliefs that CBT is useful and willingness to engage in treatment; 36.4% explained variance) and distress (discomfort from symptoms and perceived urgency to be helped; 12.7% explained variance). Higher preparedness predicted larger clinical severity reduction at post-treatment, alongside pre-treatment clinical severity. Higher distress predicted larger depression reduction at one-year follow-up, alongside pre-treatment depression. Higher preparedness predicted lower dropout. In conclusion, the NML-C comprises two factors that are differentially associated with CBT outcomes, but not above the effects of pre-treatment symptoms. Clinicians' focus on children's distress and preparedness could enhance CBT outcomes and reduce dropout.