Possible damage from the adhesive used on Post-It notes was investigated informally by the author. History of the development of Post-Its by the 3M Company is discussed. The three warnings found on the packaging indicate that the adhesive may remove correctable ink, may leave a mark on some surfaces, and should be tested before being used on questionable paper. The author collected books from the library at the National Geographic Society that had Post-Its left in them when returned. One example was found of a book that had Post-Its in place for two years. A slight adhesive residue was left. In another example, paper fibers were pulled off by a sticky tab placed on low quality paper.