A study finds that 12 percent of U.S. households now own a reading device for electronic books, such as Amazon's Kindle.
That's three times the number of households that owned an e-reader just a year ago, pointing to rapid acceptance.
The phone survey published Monday was conducted in April and May by the Pew Internet and American Life Project.
Prices for e-readers have fallen rapidly over the past year. Barnes & Noble's Nook is growing as a competitor to the Kindle. The cheapest models are now available for just above $100.
The survey also found that ownership of tablet computers such as the iPad has doubled over the past year to 8 percent of households.
The survey had a margin of error of plus or minus 2 percentage points.
Pew also asked households if they had a desktop or laptop computer, a question it has posed since 2006. Desktop households have outnumbered laptops until this year. For the first time, the two figures were within the margin of error, at 57 percent and 56 percent respectively _ a statistical dead heat. Laptop ownership has nearly doubled since 2006, while desktops have declined slightly.