To achieve water quality targets needed to support the ecological restoration of the Great Barrier Reef, increased uptake of programs aiming to change farming practices is needed. However, notwithstanding extensive research and progress in this area, knowledge gaps may be limiting the potential effectiveness of initiatives. Of particular significance is the relative paucity of reliable evidence on social and psychological factors that are theoretically known to influence the performance of a person's behaviour. This paper reports an application of the Theory of Planned Behaviour to evaluate intentions, perceived behavioural control, attitudes and social norms in changing farming practices following participation in a project aiming to enhance water quality. Overall, 23.5 % of the variance in self-reported framing practices were explained by the Theory of Planned Behaviour. The results are consistent with previous research on the influence of social norms in the adoption of behaviours, supporting a role for including social and psychological variables in farming practice change research, while simultaneously acknowledging the need for further research to draw definitive conclusions.