This study examined if beliefs about emotion change across emotional contexts in daily life, and investigated whether people with prominent features of borderline personality pathology experience greater shifts in emotion beliefs during emotional states compared to people without borderline features. Undergraduate participants with (n = 49) and without borderline features (n = 50) completed a one week ecological momentary assessment study where 7x/day they provided ratings of affect, nine different beliefs about emotion and indicators of momentary self-efficacy. Results indicated a significant between-person element to emotion beliefs, supporting the notion of beliefs as relatively schematic. In addition, people with borderline features generally experienced greater instability of beliefs over time compared to people without borderline features. In addition, most of the beliefs about emotion shifted with either positive or negative affect. For many of the emotion beliefs, the relationships between affect and belief were moderated by borderline group. Finally, momentary beliefs about emotion also predicted momentary self-efficacy for tolerating distress and exerting willpower. Taken together, results confirm that beliefs about emotion can fluctuate in daily life and that there are implications for emotion beliefs for people who struggle with emotion regulation and impulsivity (i.e., people with features of borderline personality) as well as for self-efficacy in tolerating emotion and engaging in goal-directed action.