With the rapid growth of the Internet, e-learning has been prevailed in various societies. Despite the emerging trend of using web-based learning systems to facilitate teaching and learning activities, the number of users of web-based learning systems is not increasing as fast as expected. In this research, an integrated model has been used in order to assessing the influence of IS-oriented, psychological and behavioral factors on instructors’ adoption of web-based learning systems. To examine the research model, collected data from 115 university instructors were analyzed using structural equation modeling. The results showed that subjective norm and information quality have positive effect on perceived usefulness; also, self-efficacy, service quality, subjective norm and information quality are effective on perceived ease of use. In addition, perceived usefulness, perceived ease of use and system quality all increase instructors’ intention to use web-based learning systems; however, perceived usefulness is the most important factor affecting on intention and actual use of the system (adoption).