In Cambodia, for learners of English as a Foreign Language (EFL), encountering unknown words can be a major roadblock in readingcomprehension, especially if they happen to be keywords in a particular text. The purpose of this research was to provide the information on word-attack strategy use and perceptions of unknown words in non-instructional texts of a class of sophomore students at the Institute of Foreign Languages, the Royal University of Phnom Penh (IFL-RUPP), Cambodia. It explored the differences between the three high proficient and three low proficient learners selected from the class in terms of frequency, type and outcome of strategy use, as well as how their beliefs affected their choice of strategies. In exploratory case study approach with self-reporting techniques was employed. The research instruments for data collection employed in this study were included: (1) a questionnaire on vocabulary strategy use; (2) think-aloud protocols of two reading tasks; and (3) a delayed semi-structured interview for each of the participants. The results of this research revealed that the target sophomore year class relied more on outside sources and guessing strategies, but least on strategies related to word form. The six high- and low-achievers showed considerable differences in their strategy use. The three high-achievers adopted a wider range of strategies with significantly higher frequency of use than what the three lowachievers did. The high-achievers preferred the use of the more independent strategies, but the low-achievers relied much more on outside sources, especially on the use of dictionary. The participants’ perception of the purpose of English free reading has significant impact on shaping their choices of approaches they used to cope with unknown words.