OBJECTIVES: To assess the extent to which managed care affects the utilization of antidepressants among commercially insured children and adolescents diagnosed with depression. METHODS: A sample of 5,981 children and adolescents under 18 years of age with a diagnosis of depression was identified in MedStats's MarketScan database for 1997 and 1998. The likelihood of receiving an antidepressant was studied as a logistic regression model that included structural, financial, and personal variables. A similar Cox regression analysis was conducted on a subset of 1477 subjects who were new to therapy. RESULTS: Personal variables with statistically significant odds ratios included: 1) use of other psychotropic drugs (exclusive of antidepressants), 2.50 – 3.15; 2) inpatient admission for psychiatric condition 2.45 – 3.42; 3) chronic physical comorbidity 1.03 – 1.43; 4) parent(s) with diagnosis of depression 0.71 – 0.95; and, 5) parental use of antidepressants 1.52 – 2.01. One structural variable, membership in an EPO [exclusive provider network] relative to HMO, was associated with a greater likelihood of antidepressant use, OR: 1.04 – 1.79. Structural variables that reflected membership in various plan types were important when assessing time to discontinuation. Variables with statistically significant hazard ratios included: 1) membership in an EPO, 0.39 – 0.78, and 2) POS, 0.60 – 0.92. Personal variables reflecting: 1) use of other psychotropic drugs (exclusive of antidepressants), 0.72 – 0.91, and 2) age, 1.01 – 1.05 were also significant. No financial variables (physician and pharmacy co-pay) or other structural variables (existence of a formularly and limits on mental health outpatient visits) were significant in either model. CONCLUSION: While personal factors can predict the use of antidepressants among children and adolescents with depression, plan type may be more important in predicting length of therapy. Membership in specific plan types, with different characteristics, appears to affect the time to discontinuation of antidepressants for commercially insured children and adolescents.