This classic paper raises the main problem with below-the-line expenditure: its long-term effects. Most evaluations cover a year at longest. People concerned with the saleability of a brand, with the values added by its marketing effort, with all the factors which add up to long-term profit, may feel a year is not long enough. The activities under-the-line may, as the title graphically puts it, undermine the structure which has been laboriously built up: they may drive consumers to shop by price alone, reducing a branded market to a commodity one, they may damage the ability of the brand to command a premium price and through high margins to invest in product improvement. The debate on this complex issue is not over. But this paper clarifies the issues..