It is proposed that deficient memory, particularly in regard to affect, is an important etiological factor in the development and maintenance of borderline personality disorder (BPD). The proposed memory dysfunction results in the individual living within a truncated time frame (TTF). This TTF. In turn, is shown to be adequate for explaining the characteristics of BPD (e.g., mood fluctuations, impulsive behavior, instability of self-image. intense and turbulent interpersonal relationships, and splitting). Recent neurophysiological findings with borderline individuals are briefly explored as a basis for the proposed memory dysfunction.