Objectives: This study investigated the determinants of depression in adolescents and young adults. Methods: The present study analyzed data from the 2018 Indonesia Basic Health Survey (Riset Kesehatan Dasar; RISKESDAS). The study subjects were adolescents (15-17 years old) and young adults (18-24 years old). In total, 64 179 subjects were included. Univariable, bivariable, and multivariable logistic regression analyses were performed to determine associations between youths' characteristics, risky behavior, chronic disease, parents' health, and youths' depression. Results: The prevalence of depression was 5.1% in adolescents and 5.6% in young adults. The risk factors for depression in adolescents were being women (adjusted odds ratio [aOR], 3.53; 95% confidence interval [CI], 2.89 to 4.30; p<0.001), an ex-smoker (aOR, 2.99; 95% CI, 2.10 to 4.25; p<0.001), or a current smoker (aOR, 2.60; 95% CI, 1.97 to 3.44; p<0.001); consuming alcohol (aOR, 2.00; 95% CI, 1.33 to 3.01; p=0.001), having a chronic disease (aOR, 2.64; 95% CI, 1.41 to 4.96; p=0.002); maternal depression (aOR, 2.47; 95% CI, 1.97 to 3.09; p<0.001); and paternal depression (aOR, 2.63; 95% CI, 1.98 to 3.50; p<0.001). In young adults, the risk factors were being women (aOR, 2.23; 95% CI, 1.82 to 2.75; p<0.001) or an ex-smoker (aOR, 2.47; 95% CI, 1.67 to 3.67; p<0.001), consuming alcohol (aOR, 2.42; 95% CI, 1.89 to 3.09; p<0.001), maternal depression (aOR, 3.12; 95% CI, 2.54 to 3.84; p<0.001), and paternal depression (aOR, 2.80; 95% CI, 2.17 to 3.63; p<0.001). Conclusions: Being women, smoking, drinking alcohol, having a chronic disease, and having a parent with depression were crucial factors associated with youth depression. Mental health screening, prevention, and treatment should involve collaboration among primary healthcare, schools, universities, professionals, and families.