This chapter presents a number of models useful for developing campaign strategies. These models are generally known as ‘knowledge–attitude–behaviour’ change (KAB) models or ‘social cognition’ models (Connor and Norman 2005; Godin 1994). While each can be classified as either ‘motivational’, ‘behavioural’, ‘cognitive’ or ‘affective’ in emphasis, they all deal with conceptualising the influences on behaviour, and hence provide a framework for formative research, strategy development and campaign evaluation. In general, changes in the major components in these models, such as attitudes, norms and efficacy, have been found to be good predictors of changes in behaviours and intentions (Webb and Sheeran 2006). There are a number of such models [Darnton (2008) lists and describes over thirty]. We will briefly describe each of the models most frequently mentioned in the health promotion and social marketing literature, before presenting a synthesis of the major variables across all models. We include brief discussions on two concepts generally ignored by the KAB models: morality and legitimacy (Amonini 2001). A notable omission from this chapter is Prochaska and DiClemente’s ‘Stages of Change’ model, which will be discussed in Chapter 10.