The theories of reasoned action and planned behaviour (TRA/TPB) have fundamentally changed the view that attitudes directly translate into behaviour by introducing intentions as a crucial intervening stage. Much research across numerous ethical contexts has drawn on these theories to offer a better understanding of how consumers form intentions to act in an ethical way. Persistently, researchers have suggested and discussed the existence of an intention–behaviour gap in ethical consumption. Yet, the factors that influence the extent of this gap and its magnitude have not been systematically examined. We, therefore, contribute to the debate on the intention–behaviour gap by reviewing the empirical TRA/TPB studies that have assessed both intention and behaviour in ethical contexts. The findings from our review show that few studies assessed the intention–behaviour relationship and as a result, there is limited empirical evidence to date to quantify more accurately the intention–behaviour gap in ethical consumption. Our second contribution aims to provide an empirical case study which assesses the magnitude of the intention–behaviour gap in the context of avoidance of sweatshop clothing and to assess the roles of planning and actual behavioural control in potentially reducing the intention–behaviour gap. The findings of our case study suggest that there is indeed a large gap between intention and behaviour, and we conclude by calling for more empirical longitudinal studies to assess the complex nature of the relationship between intention and behaviour.