In Linehan’s (1993) biosocial theory, borderline personality disorder (BPD) results in part from frequent, intense, negative emotions and maladaptive behavioral responses to those emotions. We conducted a secondary data analysis of an intensive single-case experimental design to explore hourly relations among behavioral responses and emotions in BPD. Eight participants with BPD (Mage = 21.57, 63% female; 63% Asian-American) reported their emotions and behaviors hourly on two days. Participants reported a neutral-to-negative average emotional state with substantial variability each day. This emotional state was characterized most frequently by anxiety and joy. Participants tended to “dig into”, or savor, experiences of joy, but problem-solve around, push away, or accept anxiety. Acceptance predicted hour-by-hour increases in negative emotion intensity, and pushing emotions away predicted hour-by-hour increases in positive emotion intensity. These results suggest that anxiety dominates the emotional experiences of people with BPD and co-occurs with a variety of emotion regulation strategies, while joy co-occurs with strategies designed to prolong emotional experiences. Despite its general adaptiveness, acceptance may be less effective, and pushing emotions away may be more effective, than other emotion regulation strategies at improving momentary negative emotions for those with BPD. We discuss the preliminary nature of these findings and encourage future researchers to build on them in larger samples with more severe presentations of BPD.