This study examined the usability of five virtual reference services--instant messenger chat, e-mail, telephone, text messaging, and Skype videoconferencing--by having 31 undergraduate and graduate students evaluate the usability of the virtual reference services of two different universities. The study's results suggest that user preference and satisfaction for virtual reference service are highly correlated with the service's overall usability in terms of effectiveness and efficiency. Online chat was rated highest across all measures including satisfaction and seven different usability factors. Major implications of the study suggest that online chat is the virtual reference of choice for university students and that usability metrics are a good predictor of user preferences centered on high return on investment, speed of transaction, convenience, and minimal effort.