Despite health intervention campaigns Department of Health (DoH) figures estimate the British public is getting more overweight (DoH, 2007). The reasons why individuals choose not to take up preventative health behaviours such as having a lower fat diet, eating five portions of fruit and vegetables a day and engaging in regular physical activity are unclear. Individual differences in personality and coping style have long been established as factors to consider in health research, however they have never been considered specifically in relation to risk factors for obesity. There is also a lack of consistency in the methods used in past studies making comparability between studies for use in designing health interventions problematic. Present research aimed to explore the efficacy of personality and coping style as predictors of diet and exercise using full scales from the Five Factor model of personality (McCrae & Costa, 1985) and the COPE inventory with added scales measuring eating and exercise as coping strategies (Carver et al, 1989; Ingledew & McDonagh, 1998). Calories from fat and fruit and vegetable consumption measures were taken from a seven-day diary in which participants recorded everything they had consumed. Daily exercise was converted into a metabolic equivalent of task (MET) score using methods taken from Godin’s Leisure Time Exercise Questionnaire (Godin & Shepherd, 1997). From previous literature it was hypothesised that the most important traits to have protective effects on health are high Conscientiousness (C) and low Neuroticism (N) (Booth-Kewley and Vickers, 1994). Higher Extraversion (E), Agreeableness (A) and Openness (O) have also all been linked with smaller, yet beneficial, effects on health behaviours linked to obesity (Lemos-Giraldez & Fidalgo-Aliste, 1997). It was additionally hypothesised that problem-focused (PF) coping, which has consistently been linked to C, would have a protective effect on health behaviours (Bermudez, 1999). Whilst avoidant coping (AV) is thought to lead to poorer diet and exercise patterns (Lindquist et al, 1997). Health behaviour measures taken from 28 participants were entered into eight separate general linear models with personality traits and coping styles as predictors. High Openness predicted that individuals were less likely to engage in exercise (F 1, 20 = 8.105, p < .05). Individuals who used problem-focused, emotion focused or used eating as a coping strategy were less likely to consume fruit and vegetables (F 1, 20 = 4.669, p < .05; F 1, 20 = 5.729, p < .05; F 1, 20 = 5.183, p < .05, respectively) whilst participants who used exercise as a coping behaviour were likely to consume more fruit and vegetables (F 1, 20 = 11.430, p < .005). No significant results were found for high C or low N as predictors of healthier diet and exercise behaviours. Tests of within-subject changes through the seven-day diary period found that there was a significant order five trend for O as a predictor of METs (F 1, 14 =13.649, p<.005, r = .494) and for A as a predictor of fruit and vegetable consumption (F 1, 14 = 4.942, p <.05, r = .261). This suggests that the effect of these personality traits on health behaviours varies over time. The present research did not find results as predicted from previous literature, however a large detrimental effect of O on METs was observed. This result indicates that all personality traits should be taken into account in health research not just the traits that are hypothesised to have the biggest effect on health. As the first study investigating personality and coping as predictors of health behaviours associated with obesity it indicates the efficacy of utilising the diary method to gain maximum amounts of health behaviour information from participants. Future exploratory research should utilise the diary method with a larger sample and a wider demographic of participants, thus furthering knowledge of the causes of individual differences in health behaviours and developing more effective interventions.