Disturbances in emotional regulation following acquired brain injury have been found to be both prevalent and particularly disabling. Despite this, relatively little attention has been given to identifying characteristics of such deficits in a systematic way. We therefore describe the development of a new questionnaire measure of disturbances in emotional regulation that may occur following acquired brain injury. The measure demonstrates excellent psychometric properties, including high test–retest (.95) and split half (.96) reliability, high internal consistency (.96), and good concurrent validity (r = .64–.82). The questionnaire measures characteristics that are distinguishable from measures of cognitive ability and from other tests of affect. There was moderate overlap between self-report and relative versions of the questionnaire. Results suggest that the relative version has the stronger predictive value. The potential uses of the measure in relation to theory and practice are discussed.