The problem considered here is the measurement of advertising effectiveness, especially when the results are to be used to help decide how much to spend and what media types to use. We have found two techniques useful: area tests; and consumer surveys in which the informants media exposure is estimated as well as her behaviour, awareness, etc. Area tests by themselves are often disappointing. Variations between areas make the results hard to interpret; tests may be abandoned or conclusions drawn from them too early. Single-source data, including media-product surveys, are now a well-understood aid to campaign planning; they are less often used but are also very helpful in post-campaign evaluation. Despite technical weaknesses and the caution needed in interpretation we have found their analysis often indicates how advertising is working. A case history is given in which media-product surveys were carried out in addition to area tests of both advertising weight and media type. Measurements made before the campaign allowed us to rule out any natural association which might have existed between media habits and product awareness. The results showed, contrary to a naive interpretation of the area test results, that press was effective in combination with television.