Objective: In daily life, we must dynamically and flexibly deploy strategies to regulate our emotions, which depends on awareness of emotions and internal bodily signals. Variability in emotion-regulation strategy use may predict fewer negative emotions, especially when people pay more attention to their bodily states-or have greater "interoceptive attention" (IA). Using experience sampling, this study aimed to test whether IA predicts variability in strategy use and whether this variability and IA together predict negative affect., Methods: University student participants ( n = 203; 165 females; Mage = 20.68, SD age = 1.84) completed trait questionnaires and reported state levels of IA, emotional awareness, negative affect, and emotion-regulation strategies, seven times daily for 1 week., Results: State IA significantly predicted between-strategy variability, which was mediated by emotional awareness (indirect effect = 0.002, 95% confidence interval = <0.001-0.003). Between-strategy variability was associated with lower negative affect, particularly when individuals had higher state IA (simple slope = -0.83, t = -5.87, p < .001) versus lower IA (simple slope = -0.31, t = -2.62, p = .009)., Conclusions: IA appears to facilitate adaptative emotion regulation and help alleviate negative affect. Findings underscore the key roles of IA and emotion-regulation flexibility in mental health., (Copyright © 2024 by the American Psychosomatic Society.)