Second-graders Arlene and Ilene Kelly are twins, identical twins to be exact, and they love being a pair. They love to dress alike, they have identical pet ferrets, and they do everything together. But being a twin is not always easy. And when Arlene gets sick and has to visit the hospital, the twins each find out what it's like to be one instead of two. But whether they're together or apart, Arlene and Ilene know they're lucky to have each other. (Back cover).