Emotion beliefs are an important mechanism associated with dysregulation of both negative and positive emotion. Positive emotions play a complex role in dysregulation, influenced by cognitive (controllability and usefulness beliefs) and behavioral factors (NSSI), underscoring the need for future research to explore dysregulation of both negative and positive emotions to improve emotional well-being.HighlightsEmotion experiences, beliefs, and NSSI are linked toand positive and negative emotion dysregulation.Extended emotions responses are linked to dysregulation only in the context of believing emotions areuncontrollable.Similar emotion beliefs relate differently to experiences and dysregulation depending on NSSI status.