Whereas time trends in the epidemiologic burden of US pediatric mental health disorders are well described, little is known about trends in how these disorders are studied through clinical research. We identified how funding source, disorders studied, treatments studied, and trial design changed over the past decade in US pediatric mental health clinical trials. We identified all US pediatric interventional mental health trials submitted to ClinicalTrials.gov between October 1, 2007 and April 30, 2018 (n = 1,019) and manually characterized disorders and treatments studied. We assessed trial growth and design characteristics by funding source, treatments, and disorders. US pediatric mental health trials grew over the past decade (compound annual growth rate [CAGR] 4.1%). The number of studies funded by industry and US government remained unchanged, whereas studies funded by other sources (e.g., academic medical centers) grew (CAGR 11.3%). Neurodevelopmental disorders comprised the largest proportion of disorders studied, and Non-DSM-5 (Diagnostic and Statistical Manual-5) conditions was the only disorder category to grow (14.5% to 24.6%; first half to second half of decade). There was significant growth of trials studying non-psycho/pharmacotherapy treatments (33.8% to 49.0%) and a decline in trials studying pharmacotherapies (31.7% to 20.6%), though these trends differed by funding source. There were also notable differences in funding sources and treatments studied within each disorder category. Trials using double blinding declined (26.2% to 18.0%). Limitations include that ClinicalTrials.gov is not an exhaustive list of US clinical trials, and trends identified may in part reflect changes in trial registration rather than changes in clinical research. Nevertheless, ClinicalTrials.gov is among the largest databases available for evaluating trends and patterns in pediatric mental health research that might otherwise remain unassessable. Understanding these trends can guide researchers and funding bodies when considering the trajectory of the field.