Extended maternal separations before age 5 were evaluated as a predictor of long-term risk for offspring borderline personality disorder (BPD) symptoms in longitudinal data from a large random community sample. Early separations from mother predicted elevations in BPD symptoms assessed repeatedly from early adolescence to middle adulthood. Early separations also predicted a slower than normal rate of decline in symptoms with age. Other theoretically grounded risks were examined and shown to predict elevated BPD symptoms over the developmental trajectory. Long-term effects of early separations were largely independent of childhood temperament, child abuse, maternal problems, and parenting risks. These data provide the first prospectively collected data on the developmental course of BPD symptoms and suggest a series of environmental and other influences on these very disabling problems.