This paper introduces the Book Structure Extraction competition run at ICDAR 2009. The goal of the competition is to evaluate and compare automatic techniques for deriving structure information from digitized books, which could then be used to aid navigation inside the books. More specifically, the task that participants are faced with is to construct hyperlinked tables of contents for a collection of 1,000 digitized books. This paper describes the setup of the competition, the book collection used in the task, and the proposed measures for the evaluation. Results of the evaluation will be presented at the ICDAR 2009 conference and will be published in the INEX 2009 proceedings.