Borderline personality disorder (BPD) is a frequent and severe pathology. Although BPD is mostly diagnosed in adults, evidence shows that it can also be adequately diagnosed in adolescents. However, several obstacles seem to prevent this diagnosis from being made on patients younger than 18. Aside from the fact that drawing a line between borderline personality features and the transitional adolescent turmoil could be complicated, some health professionals are reluctant to make a diagnosis that stigmatizes their patients, especially the youngest ones. However, being able to identify and treat BPD during this developmental stage would reduce many adverse outcomes in the long run. Achieving early detection requires reliable and valid tools to screen and diagnose BPD in adolescents. The aim of this article is not only to review studies reporting on difficulties to diagnose BPD in adolescents but also to highlight some realistic solutions. We explain in detail how BPD symptoms manifest during adolescence. We also present the tools currently available to assess and diagnose this pathology in adolescents.