As reading-on-screen (RS) becomes more and more common nowadays, many ESL graduate students are struggling with RS, especially for academic purposes in English as a second language. This struggle greatly affects these students' learning performance in an environment where many learning activities (e.g., reading, writing, discussion board in learning management systems) were carried out on screens (Chou, 2012). Researchers support that when a second language is involved, RS becomes more complex, challenging, and demanding because processing reading materials in a second language could potentially increase readers' cognitive load and affect their reading performance (Chou, 2012; Kennedy, 2001). However, research that specifically and closely examines RS for English-as-a-second-language (ESL) graduate students is scarce. Without more comprehensive knowledge of RS in an ESL context, ESL graduate students' ability to read on screen effectively and teachers' ability to help these students become successful readers on screen are severely compromised (e.g., Gilbert, 2017; Rimi, 2019). Inspired by the literature in the field of RS and reading in general, and informed by sociocultural theory, this case study focused on ESL graduate students' frequency and perception of RS and reading-English-on-screen (RES). This study paid attention to not only "now" (ESL graduate students' frequency of use and perception of RS), but also the "past" (students' past experience and how it leads to "now"). Two research questions guided this study were: RQ1. What are focal ESL graduate students' current reading frequency and perception of RS and RES? RQ2. Looking back at selected ESL graduate students' past experience, what factors helped to shape their perception of RS and RES? To answer the two research questions, the researcher distributed questionnaires that measured and compared students' frequency and comfort level of RS and RES. Sixty-seven responses were collected. Moreover, the researcher conducted in-depth interviews with ten of the 67 respondents to examine their past experience and their perception of RS and RES. Questionnaire responses and part of the interview data informed the first research question. The rest of the interview data was used to answer the second research question. The findings showed participants spent more time reading on screen while they were more comfortable with RP. They also perceived both advantages and disadvantages of RS and RES. Moreover, the interviewees' perceptions of RS and RES appeared to mainly be affected by factors such as their familiarity with technology (sometimes relative to what they wanted to achieve when reading on screen) and their perceived difficulty of reading tasks in terms of content and language (sometimes relative to what they want to do for RS). Besides, some interviewees also showcased how perception and experience of RP, as well as personality, could possibly change their perception of RS and RES but these claims appeared to be more trivial. These factors were related to and shaped by the interviewees' past experiences such as the family influence, the societal influence, or a change in environment brought either by technology advancement or physical relocation. Other past experience such as extensive gameplay experience also contributed to some interviewees' personality formation and subsequently affected the factors mentioned above. The interviewees' perception to some extent determined whether they read on screen and how often they read on screen. Meanwhile, the actual choice and frequency of RS also appeared to be determined by both perception toward RS, as well as practical concerns such as the interviewees' socio-economic status in relation to the cost of printing and paper-based reading materials. Implications based on the findings in terms of screen design and RS and RES reading strategies were discussed in the dissertation. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]