Current U.K. guidelines on the management of borderline personality disorder include specific recommendations about the duration of therapy and number of sessions per week that patients should be offered. However, very little research has been conducted to examine the impact of these aspects of treatment process on patient outcomes. We therefore undertook a systematic review to examine the impact of treatment duration, number of sessions per week and access group-based therapy on general mental health, depression, social functioning and deliberate self-harm. We identified 25 randomized trials for possible inclusion in the review. However, differences in outcome measures used meant that only 12 studies could be included in the analysis. Statistically significant reductions in self-harm and depression and improvement in social functioning were found for treatments that include more than one session per week and those that included group-based sessions but were not found for those that deliver in individual sessions or one or fewer sessions per week. Longer term outcomes of short-term interventions have not been examined. Further research is needed to examine the impact of shorter term interventions and to compare the effects of group-based versus individual therapies for people with borderline personality disorder.