Importance Extant treatments for youth depression are only modestly effective. Alternative approaches are needed to improve health outcomes. A novel approach to improve depression outcomes is suggested by epidemiological studies finding that insomnia often predates and may contribute to depression risk. We test whether treating insomnia among youth starting a new course of SSRI antidepressants improves depression outcomes. This paper describes our study design. Design 2-arm randomized controlled efficacy-effectiveness trial. Setting A large non-profit health maintenance organization. Participants 165 adolescents aged 12–19 with research-confirmed depression and insomnia diagnoses, starting a new episode of selective serotonin reuptake inhibitor (SSRI) antidepressant treatment prescribed by their usual care provider. Interventions Two sleep interventions, each 6–7 sessions, both overlaying “treatment as usual” (TAU) SSRIs: a sleep hygiene (SH) attention control condition, and cognitive-behavioral therapy for insomnia (CBT I). Conclusions and relevance If CBT-I improved sleep is shown to improve depression-related outcomes, this may provide an additional, easily tolerated intervention for an important public health target. Trial Registration: clinicaltrials.gov , NCT02290496 , https://clinicaltrials.gov/ct2/show/NCT02290496 .