For the first time in the eight years that the NPD Group has been measuring trends among American book buyers, the number of adult books bought fell. According to the results of the 1998 Consumer Research Study on Book Purchasing, the unit purchases of adult books decreased 2.8% to 1.04 billion last year. In 1997, unit sales inched up by less than 1%.

The mass market paperback segment had the largest decline, representing about two-thirds of the overall drop in purchases. Hardcovers accounted for most of the remaining balance, with trade paperback unit sales holding about even.

The drop in mass market paperback purchases was reflected in changes in the market share among the different distribution channels. Sales through the used bookstores and food/drug stores -- outlets that focus on mass market titles -- saw a significant drop in market share during the year. Book clubs also saw a sharp decline in units, with their market share falling last year to 18% from 1997's 20%.

At the bookstore level, the chains had a 0.2% increase in their piece of the market last year, while independents saw their share fall 0.6%. Book sales through the Internet rose from less than 1% in 1997 to nearly 2% in 1998.

At a press conference held during BEA, Sandy Paul of the Book Industry Study Group, one of the sponsors of the study, noted that book buying appears to be countercyclical. With a booming economy, consumers seem to be more willing to spend their disposable income on higher-priced items than they are in leaner times, during which books are viewed as an inexpensive gift or form of personal entertainment.

The full report will be published before the end of the month and is available from BISG.