Purpose <p>The Patient Health Questionnaire-9 (PHQ-9) is a widely used self-report tool for screening depressive symptoms. However, several psychometric studies have raised concerns about its diagnostic accuracy. The Composite International Diagnostic Interview Short Form Self-Report (CIDI-SF-SR) is increasingly used in epidemiological surveys because it uses the diagnostic criteria for Major Depressive Disorder (MDD). In this study, we aimed to compare the concordance between the PHQ-9 and CIDI-SF-SR to assess the presence of depression in young adults.</p> Methods <p>Data were obtained from a national study on the mental health of midwifery students (<i>n</i> = 1,797). Participants completed both the PHQ-9 and the CIDI-SF-SR. While the PHQ-9 assessed the presence of symptoms over the past two weeks, the CIDI-SF-SR covered both the past two weeks and the past year.</p> Results <p>The prevalence of depressive symptoms was 44% using the PHQ-9 (cut-off ≥ 10), compared to the 7% and 13% MDD prevalence with the CIDI-SF-SR for the past 2 weeks and 12 months, respectively. The concordance between the two scales was around 60%. Adding functional impairment to the standard PHQ-9 algorithm improved concordance classification to 90%. The optimal cut-off point, comparing PHQ-9 to CIDI-SF, was ≥ 15.</p> Conclusion <p>This study is the first to compare the PHQ-9 to the CIDI-SF-SR in a large sample of young adults. Compared to the CIDI-SF-SR, using the standard scoring of the PHQ-9 resulted in a 6-fold increase in the prevalence of depressive symptoms. This study could facilitate comparisons between studies using these two instruments and be useful for future meta-analysis.</p>