Objectives: This paper describes a composite 'Prudence Score' summarising self-reported behavioural risk factors for non-communicable diseases. If proved robust, the 'Prudence score' might be used widely to encourage large numbers of individuals to adopt and maintain simple, healthy changes in their lifestyle. Methods: We calculated the 'Prudence Score' based on responses collected in late 2006 to a postal questionnaire sent to 225 adult patients aged 25 to 75 years identified from the records of two general medical practices in Brisbane, Australia. Participants completed the behavioural, dietary and lifestyle items in relation to their spouse as well as themselves. The spouse or partner of each addressee completed their own copy of the study questionnaire. Results: Kappa scores for spousal concordance with probands' reports (n = 45 pairs) on diet-related items varied between 0.35 (for vegetable intake) to 0.77 (for usual type of milk consumed). Spousal concordance values for other behaviours were 0.67 (physical activity), 0.82 (alcohol intake) and 1.0 (smoking habits). Kappa scores for test-retest reliability (n = 53) varied between 0.47 (vegetable intake) and 0.98 (smoking habits). Conclusion: The veracity of self-reported data is a challenge for studies of behavioural change. Our results indicate moderate to substantial agreement from life partners regarding individuals' self-reports for most of the behavioural risk items included in the 'Prudence Score'. This increases confidence that key aspects of diet and lifestyle can be assessed by self-report. Implications: The 'Prudence Score' potentially has wide application as a simple and robust tool for health promotion programs.