The ability to control our thoughts and actions is broadly associated with health and success, so it is unsurprising that measuring self-control abilities is a common goal across many areas of psychology. Puzzlingly, however, different measures of control - questionnaire ratings and computerized cognitive tasks - show only weak relationships to each other. We review evidence that this discrepancy is not just a result of poor reliability or validity of ratings or tasks. Rather, ratings and tasks seem to assess different aspects of control, distinguishable along six main dimensions. To improve the psychological science surrounding self-control, it will be important for future work to investigate the relative importance of these dimensions to the dissociations between self-control measures, and for researchers to motivate and explain which aspects of control they are studying when one or both types of measures are deployed. Keywords: cognitive control, executive function, self-regulation, self-control, impulsivity.