This paper reports on an evaluation of the test-retest reliability and internal consistency of the Human Aspects of Information Security Questionnaire (HAIS-Q), a measure designed to capture an individual’s knowledge, attitude and self-reported behaviour towards information security in the workplace. The analyses focused on responses from 197 working Australians, who completed two iterations of the HAIS-Q, approximately four weeks apart. The HAIS-Q showed significant test-retest correlations and has high internal reliability levels. The results of this study demonstrated that the HAIS-Q possesses both external reliability and internal consistency, and can therefore be used as a reliable measure of information security awareness. The HAIS-Q can be used within organisations to measure the effectiveness and impacts of training interventions, information security awareness programs and to determine the impact of security incidents and cultural changes.