The research streams on the technology acceptance model (TAM) 4 and usability have traditionally been independent. Yet both streams of research focus on the users’ perception of technology. A unified model would clarify the relationship between usability and technology acceptance. In this study we proposed a unified model to investigate the relationship between perceptual measures used in TAM studies and perceived usability of ERP documentation (See Figure 1). Results from a survey of ERP users at a large university showed that perceived usefulness of the documentation had a strong relationship with its perceived usability. Also users rated the documentation poorly for helping them understand business processes. Documentation usability would improve with an emphasis on support for relevant new tasks and explanation for the rationale of the transformed process. 2, 4, 6