A number of recent reports have indicated that there is a high incidence of sexual abuse during childhood among patients with borderline personality disorder. Although these findings are important, a simple association between abuse and the disorder is an oversimplification. Community studies of the long term effects of abuse indicate that the parameters of abuse are crucial to the patient's outcome. In addition, correlations have been found between sexual abuse during childhood and factors related to the family environment. A multifactorial model of the etiology of borderline personality disorder is proposed in which biological vulnerability, psychological factors and social influences are considered along with their interactions.