This investigation attempts to improve understanding of the behaviour of internet consumers from an empirical basis. It reports on the results of studies into decision-making processes of consumers on the internet in the context of apparel retailing. Consumers consisting of a profile sample of working female consumers, aged between 18 and 45, in the ABC1 social group, are considered in terms of their decision making processes online. These observations are contrasted with the assumptions underlying a key reference model of traditional consumer behaviour, the Consumer Decision Process (CDP) model (Blackwell, Engel & Miniard, 2001). The research arrives at several key findings. A primary finding is that there are substantive differences between internet-based and traditional decision making purchases - especially when considering consumers’ behaviour in relation to so-called sensory products. A related finding is that many of the assumptions underlying the CDP model fail to explain many aspects of observed internet consumers’ behaviours in this respect. The observed incongruence is addressed by the thesis through fundamental revisions and extensions of the CDP model. Three key changes proposed include: the introduction of the concept of overlapping stages (where two decision-making stages can occur together); the notion of varying modalities of behaviour depending on a consumer's intentions, and the possibility of a shift in modality during the purchasing process. These notions are incorporated in a proposed model referred to as the Electronic Consumer Decision Process model (eCDP).