This paper is divided into three sections. The first deals with some of the main points derived from the Adams Readers' Panel which bear on the title. The marketing of books is an order of magnitude more difficult than the marketing of most products, in the sense that each product is different from every other; each package is different; and price and promotion, although more uniform, still vary greatly. What the Panel can do to help is largely to shed fresh types of light on the readers' attitudes to these variables. The second deals with other findings, concerning particularly other book reading and reading of newspapers and magazines. We illustrate the diversity of reading patterns, both of books and journals, and show that, in general, heavy readers of books tend to be heavy readers of printed matter. The third deals with the mechanics of setting up and operating the Panel. We comment on bias accidentally introduced by the choice of incentive (and how changes in wording affected response); on the very high quality of write-in response, in general; the patterns of scoring, within books and within panellists; and the generally satisfactory levels of response and maintenance.