This article reviews the putative role of emotion dysregulation in diverse clinical presentations and considers some of its aetiological factors, such as insecure attachments in early life and traumatic experiences in later life. The neurobiology of emotional processes is described in relation to the ‘window of tolerance’ model of arousal levels optimal for information processing. Treatment options are considered and ways to regulate distress, derived from different approaches, are summarised in a ‘toolbox’. Fictitious case vignettes illustrate clinical applications.