From the official Oregon Battle of the Books website:
The Oregon Battle of the Books, OBOB, is a statewide voluntary reading motivation and comprehension program sponsored by the Oregon Association of School Libraries in conjunction with a Library Services and Technology Act grant. Students in 3rd-12th grade, regardless of ability, are exposed to quality literature representing a variety of literary styles and viewpoints. The mission is to encourage and recognize students who enjoy reading, to broaden reading interests, to increase reading comprehension, promote academic excellence, and to promote cooperative learning and teamwork among students.
OBOB at CSS
The main goals of Battle of the Books are to have fun, shared reading experiences and to be exposed to a wide variety of quality literature. There are two different levels of participation. The first is to just read the books! The list is always well-stocked with some good reads. The other is to form a team (with up to three other people of any class or grade in your division) and compete in the school OBOB tournament, usually held in late January to mid-February. The winner of that competition goes to to the regional tournament, which normally occurs in the first two weeks of March.