Sun protective attitudes and intentions were investigated in 2 experiments and 1 field study. Participants in the first experiment were female Caucasian university students between the ages of 17 and 35 years (N = 102). A 2 x 2 experimental design manipulated message frame and the normative context and measured the level of identification with the ingroup (university students) to examine intentions to engage in sun protective behaviour within the next fortnight and within the next month. To manipulate levels of ingroup normative support, participants studied bar graphs and testimonial statements showing ostensible information on the percentage of recreational sportswomen engaging in sun-protective behaviours in comparison to non-sporting women. To manipulate the message frame, messages were presented in either a gain or loss frame format. Regression analyses revealed significant effects for prior attitudes towards engaging in sun-protective behaviour in the next fortnight and also in the next month. Contrary to expectations, no interactive effects involving norms were found in the prediction of intentions. The lack of significant results were attributed to the unsuitability of the sample population (university students) in relation to sun-protective behaviours. To test third person perceptions, two measures of perceptions of influence were assessed. The first measure assessed perceptions of how much the target groups would be affected by the sun-protective advertisement and the second assessed perceptions of how much target groups would engage in regular sun-protective behaviour after reading the sun-protective advertisement. Results of the repeated measures mixed ANOVAS revealed reversed third person perceptions between self and other when participants were exposed to a supportive ingroup norms and a Sun-protective attitudes and behaviours vi classic third person effect when participants were exposed to a non-supportive ingroup norm. Similar patterns of results were found for perceptions between ingroup and outgroup members. It was concluded from study one that the manipulations due to ingroup norms may not have been effective for a sample of participants whose personal relevance for sun-protective behaviour was not strong. In study 2, sun protective attitudes, intentions and behaviour at a 2-week follow-up were investigated in an experimental study using a population more likely to engage in decision-making in relation to the target behaviour; Caucasian sportswomen between the ages of 17 and 35 years (N = 101). The 2 x 2 experimental design manipulated the normative context and image norms and measured the level of identification with ingroup (young recreational sportswomen). Ingroup norms were manipulated in a similar manner to study 1. Image norms were manipulated through the inclusion of a colour photograph featuring a sportswoman whose skin tone had been manipulated via a computer imaging program (Photoshop 6.0) to appear either pale or tanned. Regression analyses revealed a significant 2-way interaction for ingroup norm x identification on intentions. When decomposed, the interaction showed that participants who identified strongly with their ingroup had stronger intentions to engage in sun-protective behaviour in the next fortnight when exposed to a supportive ingroup norm. The findings lend support to the impact of social influence on intentions to engage in sun-protective behaviours. A trend was also revealed for the 2-way interaction for group norms x image norms on attitudes towards engaging in sun-protective behaviour in the next fortnight. The trend suggested that participants exposed to a pale image norm had more positive attitudes towards engaging in sun-protective behaviour when exposed to a supportive group norm in comparison to those exposed to a non-supportive group norm. Sun-protective attitudes and behaviours vii Thus, study 2 provided support for the interactive effects of ingroup norms and identification on intentions to engage in sun-protective behaviours suggesting that group norms, conceptualised from a SIT/SCT perspective, may be important in the sun-protective decision-making process. Study 2 also provided some support for the interactive effects of ingroup norm and image norms on attitudes towards engaging in sun-protective behaviours, highlighting the importance of investigating the effects of social influence factors in young sportswomen's sun-protective decision making processes. In study 3, participants were Caucasian women between the ages of 17 and 35 years (N = 123) who were visitors to beaches on the Sunshine Coast, Queensland, Australia. A model based on the theory of planned behaviour (Ajzen, 1991) was developed incorporating additional normative factors (i.e., image norms, group norms and personal norms). The revised TPB model was then compared to two models previously tested in the context of health behaviours. The first comparative model was based on Jackson and Aiken's (2000) psychosocial model of sunprotection and, the second model was based on Gibbons, Gerrard, Blanton and Russell's (1998) prototype/willingness model. The models were examined using the EQS structural equation modelling program which revealed that the TPB-based model provided the most parsimonious fit to the data. The results support the inclusion of different sources of social influence (i.e., group norms and personal norms) in a TPB-based predictive model for sun-protective intentions and behaviours. Results revealed it is important to consider the impact of group norms, from a SIT/SCT perspective, on young women's sun-protective decision-making processes. Results also showed that it is important to consider the impact of young women's personal norms (i.e., internal moral rules and expectations about their own Sun-protective attitudes and behaviours viii behaviour) in the sun-protective decision-making process. Overall, the findings of the program of research suggested that it was specific referent norms that were important in the sun-protective decision-making process rather than more broad and general societal norms. Overall, the program of studies established the important role of social influence factors in young women's sun-protective decision making processes. The program of studies highlighted important theoretical and practical contributions that can aid in the development and implementation of more effective sun-protection messages to motivate young women to engage in sun-protective behaviours. The current program of research adds to the field of research by providing a comparison of the impact of various sources of social influence on attitudes and intentions to engage in sun-protective behaviour. The current research also empirically elucidates the core dimensions, mechanisms and relationships underlying the formation of sunprotective attitudes, intentions and behaviours.