Despite the widely reported increase in environmental concern amongst consumers, a gap exists between their stated intentions to purchase environmentally-friendly products and their actual purchase behaviour. The current study tests a conceptual model developed by Carrington, Neville and Whitwell (2010) to help explain this gap. Surveys were administered to a sample of university students. Responses (N=272) showed that implementation intentions had a mediating effect on the relationship between intention and behaviour. Situational (social) context was found to moderate the relationship between intention and implementation intentions. Behavioural control, on the other hand, had no moderating effect. The findings have theoretical implications for furthering understanding of factors impacting pro-environmental consumer behaviour, and practical implications regarding how to positively influence socially beneficial behaviours.