Motivation in general is one of the most important components of the process of learning and teaching in any educational environment, and it can explain the success or failure of student. In online learning, learners tend to study on their own and intrinsic motivation is particularly the main source that triggers and sustains learning process (Hartnett, 2016; Johnson et al., 2015; Shroff et al., 2007). Therefore, learners need high levels of intrinsic motivation to ensure success in their studies. Despite the emerging research regarding online learning, little attention has been given to graduate students' intrinsic motivation in online courses. Therefore, using a mixed methodology approach, this study aimed to gain a deeper understanding of the nature of intrinsic motivation in fully online courses environment. A sample of 127 graduate students first responded to Intrinsic Motivation in e-Learning IMeL questionnaire in order to answer the first two research questions which are (1) What is the level of graduate students' intrinsic motivation in fully online courses? (2) Is there a significant difference in the level of graduate students' intrinsic motivation in fully online courses in terms of: (gender, registration status, employment status, and experience with fully online courses)? Afterwards, 10 participants who completed the questionnaire participated in follow-up interviews about their intrinsic motivation in in fully online courses. Findings revealed that graduate students had high level of intrinsic of motivation in online courses environment. In addition, the study found that there is a statistically significant difference in the level of graduate students' intrinsic motivation in fully online courses in terms of gender. It was also found that there are no statistically significant differences in the level of graduate students' intrinsic motivation in fully online courses in terms of registration status, employment status, and experience with fully online courses). Furthermore, in-depth interviews uncovered a number of factors that are highly related to graduate students' intrinsic motivation in fully online courses. Findings, implications, limitations and future directions are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]