The subject of brand extensions is looked at and, in particular, the idea of 'brand stretching', in order to answer the question, "How far can a mother brand stretch, by extending itself within and across brand categories and sub-categories?" The work of David Aaker, a major contributor to the whole area of brand equity is discussed in detail, and some of Aaker's ideas have been developed in order to establish a practical method for determining the 'fit' (Aaker) between a mother brand and the object of its intended extension. An approach to measuring fit, using an implicit model of personality, was employed to show (a) whether 'brands' of banks present in Turkey would be able to successfully stretch into different financial services; and (b) whether different brands of milk could stretch into other milk- based product categories. The amount of data generated from this R & D study was enormous and only a small number of examples can be discussed. In the case of financial services, automatic teller machines are looked at to see if bank brands could stretch into providing an Automatic Teller Machine service. In the case of milk-based products, butter and margarine are considered.