Systems Training for Emotional Predictability and Problem Solving (STEPPS) for borderline personality disorder (BPD) has been adapted for a primary care setting into a 13-week group treatment for emotional intensity difficulties (STEPPS EI). This is the first study to examine the effectiveness and potential outcome and dropout predictors of STEPPS EI in a primary care setting. Severity of BPD, depression, and anxiety symptoms were measured pre- and postintervention for 148 participants. Treatment completers showed improvements in depression, anxiety, and BPD symptoms with medium to large effect sizes. A predictor of symptom improvement was higher baseline severity for each of the symptom measures. Attending a psychoeducational group prior to STEPPS EI was associated with lower odds of dropout. The findings support the use of STEPPS EI in a primary care setting, with the potential to alleviate the burden from other local services.