We found in Chapter 2 that a major aim of housing policy in the countries of the European Union has been to secure decent housing for all households at a price within their means. When the price is not 'within their means' it can be argued that there is an 'affordability' problem. In Chapters 3 and 4 we identified some of the policy instruments that can be used to close the gap between the cost of providing rented housing of an acceptable standard and what households are able to pay. The basic elements of affordability have thus already been outlined. The affordability problem has, however, become such a focus of attention in the UK and other countries, that we now examine the concept of affordability in more depth.