Borderline personality disorder (BPD) has historically been seen as a lifelong, highly disabling disorder. Research during the past 2 decades has challenged this assumption. This paper reviews the course of BPD throughout life, including childhood, adolescence, and adulthood. BPD can be accurately identified in adolescence, and the course of the disorder, in adolescence and adulthood, is generally similar, with reductions in symptoms over time. Functional recovery is less consistent, and further research on factors or treatments that may improve the long-term functional outcome of patients with BPD is warranted.