Importance: The prevalence of adolescent depression and other internalizing mental health problems has increased in recent years, whereas the prevalence of externalizing behaviors has decreased. The association of these changes with the use of mental health services has not been previously examined., Objective: To examine national trends in the care of different mental health problems and in different treatment settings among adolescents., Design, Setting, and Participants: Data for this survey study were drawn from the National Survey on Drug Use and Health, an annual cross-sectional survey of the US general population. This study focused on adolescent participants aged 12 to 17 years interviewed from January 1, 2005, to December 31, 2018. Data were reported as weighted percentages and adjusted odds ratios (aORs) and analyzed from July 20 to December 1, 2019., Main Outcomes and Measures: Time trends in 12-month prevalence of any mental health treatment or counseling in a wide range of settings were examined overall and for different sociodemographic groups, types of mental health problems (internalizing, externalizing, relationship, and school related), and treatment settings (inpatient mental health, outpatient mental health, general medical, and school counseling). Trends in the number of visits and nights in inpatient settings were also examined., Results: A total of 47 090 of the 230 070 adolescents across survey years (19.7%) received mental health care. Of these, 57.5% were female; 31.3%, aged 12 to 13 years; 35.8%, aged 14 to 15 years; and 32.9%, aged 16 to 17 years. The overall prevalence of mental health care did not change appreciably over time. However, mental health care increased among girls (from 22.8% in 2005-2006 to 25.4% in 2017-2018; aOR, 1.11; 95% CI, 1.04-1.19; P = .001), non-Hispanic white adolescents (from 20.4% in 2005-2006 to 22.7% in 2017-2018; aOR, 1.08; 95% CI, 1.03-1.14; P = .004), and those with private insurance (from 19.4% in 2005-2006 to 21.2% in 2017-2018; aOR, 1.11; 95% CI, 1.04-1.18; P = .002). Internalizing problems, including suicidal ideation and depressive symptoms, accounted for an increasing proportion of care (from 48.3% in 2005-2006 to 57.8% in 2017-2018; aOR, 1.52; 95% CI, 1.39-1.66; P < .001), whereas externalizing problems (from 31.9% in 2005-2006 to 23.7% in 2017-2018; aOR, 0.67; 95% CI, 0.62-0.73; P < .001) and relationship problems (from 30.4% in 2005-2006 to 26.9% in 2017-2018; aOR, 0.75; 95% CI, 0.69-0.82; P < .001) accounted for decreasing proportions. During this period, use of outpatient mental health services increased from 58.1% in 2005-2006 to 67.3% in 2017-2018 (aOR, 1.47; 95% CI, 1.35-1.59; P < .001), although use of school counseling decreased from 49.1% in 2005-2006 to 45.4% in 2017-2018 (aOR, 0.86; 95% CI, 0.79-0.93; P < .001). Outpatient mental health visits (eg, private mental health clinicians, from 7.2 in 2005-2006 to 9.0 in 2017-2018; incidence rate ratio, 1.30; 95% CI, 1.23-1.37; P < .001) and overnight stays in inpatient mental health settings (from 4.0 nights in 2005-2006 to 5.4 nights in 2017-2018; incidence rate ratio, 1.18; 95% CI, 1.02-1.37; P = .03) increased., Conclusions and Relevance: This study's findings suggest that the growing number of adolescents who receive care for internalizing mental health problems and the increasing share who receive care in specialty outpatient settings are placing new demands on specialty adolescent mental health treatment resources.