Abstract Previous research indicates that the Mood Disorder Questionnaire (MDQ), the Internal State Scale (ISS), and the Hypomanic Personality Scale (HPS) have the capacity to assess symptoms of bipolar spectrum disorders. The present study cross-validates these scales in a sample of 167 undergraduate students. Individuals were divided into high, medium and low likelihood of caseness (HLC, MLC and LLC) groups based on operationalised cut-off criteria on the MDQ. Scores on the ISS Perceived Conflict subscales were positively and proportionately associated with elevated likelihood of caseness. The HLC group was distinguished from the other two groups by high levels of ISS Depression, whereas the LLC group was distinguished from the other two groups by low levels of ISS Activation and hypomanic personality traits. The majority of individuals reported a history of isolated (hypo)manic experiences, and a quarter of the sample reached screening criteria for a bipolar spectrum disorder ( Isometsae et al., 2003). The results are discussed in the context of the role of activation, depression, and interpersonal conflict in bipolar spectrum disorders.