Self-discrepancy theory [E. T. Higgins, 1987] proposes that discrepancies between self and 'ideal' standards are associated with dejection-related emotions, whereas discrepancies between self and 'ought' standards are associated with agitation-related emotions. Although there is substantial evidence to support the ideal/ought distinction, the traditional method used to measure self-discrepancies contains some theoretical and conceptual limitations. This paper discusses these limitations, presents a critique of other methods of measuring self-discrepancies and suggests a new measurement technique, the Self-Lines measure. This new approach is consistent with the theoretical underpinning of self-discrepancy theory. A pilot study suggests that this approach is feasible and two comparative studies demonstrate the validity and advantages of the Self-Lines measure.