Many schools and universities are starting to offer e-textbooks as an alternative to traditional paper textbooks;

however, limited research has been done in this area to examine their usability. This study aimed to investigate the usability of eight e-textbook reading applications on a tablet computer using the Technique for Human Error Assessment (THEA). The tasks investigated are typical of those used by college students when reading a textbook (bookmarking, searching for a word, making a note, and locating a note). Recommendations for improvement of the user experience of e-textbook applications are discussed along with tips for usability practitioners for applying THEA.