OBJECTIVES: To evaluate the effectiveness of managing depression on a population-level using myStrength, a digital self-care behavioral health and well-being platform. An effect size model was developed to compare the impact of myStrength on depression symptom burden reduction relative to the effectiveness of psychotherapy, the standard of care. METHODS:  This study quantified the normalized effect size achieved for 1,143 commercially-insured adults using myStrength’s self-help tools, who initially demonstrated some depression, the intervention group. The DASS-21 measured self-reported baseline symptom severity among the intervention group. Consumers with mild or greater symptom severity were included in the analysis and were prompted to complete assessments at 14, 60, 180 and 365 days post-baseline. The difference between baseline and YTD last assessment quantified the change in depression symptom severity score. The effect size was estimated as the mean change in depression score divided by the average difference in standard deviation from baseline to last assessment. The comparator group, psychotherapy, was assumed to have an effect size of between 0.5 - 0.8 based on the literature. RESULTS:  Of the 1,143 myStrength consumers with some baseline level of depression, 78% were female and the mean age was 45.70 years. On average, myStrength consumers accessed the platform 4.75 times in their first 30 days. The mean depression score was 21.50 among myStrength consumers at baseline (median = 20; standard deviation = 9.41). At last assessment, the mean depression score decreased to 16.10, demonstrating symptom burden reduction among the intervention group (median = 14; standard deviation = 11.87). The myStrength estimated effect size was 0.49 [95% CI: 0.41, 0.57]. CONCLUSIONS: Among a commercially-insured, adult population with some degree of depression, myStrength was shown to be at least 61% as effective as traditional psychotherapy. Depression management may benefit from expanding behavioral healthcare offerings to include digital platforms.