Dramatic structural changes are taking places within the rapidly growing web advertising sector, the most notable being the rise to prominence of Keyword Search Advertising (KSA). KSA emerged from the pressure to create new, more effective and non-intrusive web advertising formats. Presumably, advertisers prefer KSA because of favourable consumer responses but it seems that no scholarly research has explored such consumer behaviour. The purpose of this research is to propose a theoretical model identifying the impact of KSA on consumers' cognitive and behavioural responses.