In the field of second language acquisition (SLA), "comprehensible input" (Krashen, 1985) has been considered a critical factor to help learners acquire foreign and second languages (L2). From this perspective, the notion of extensive or free voluntary reading (Day & Bamford, 1998; Krashen, 1993) has emerged that L2 learners should be given more pleasure reading by minimizing a burden look-up behavior. At the same time, technology innovation has made it possible for extensive reading to occur through technology over the past decades. In particular with hypertext glosses or multimedia annotations, a number of studies have indicated that hypertext glossed input is comprehensible input and has made it possible for L2 readers to benefit all from extensive reading. This study examines (1) effects of hypertext gloss use on L2 vocabulary acquisition in computerized reading contexts, and (2) which specific combination of either text-only (single) or text + visual (multiple) hypertext glosses is more effective on L2 vocabulary acquisition and 3) What potential moderators to systematically account for between study variation are. In addition, it aims to synthesize characteristics of studies, technology use and research methods from empirical research studies for a comprehensible and insightful review of the effect of hypertext glosses on L2 vocabulary acquisition. Meta-analysis as a quantitative method was conducted to synthesize overall findings of empirical studies by calculating a standardized mean difference effect size. From 300 papers considered, 10 met the "Criteria for Inclusion" through a final filtering process, and were finally meta-analyzed to extract effect sizes in the present study. On the basis of 35 weighted mean effect size, 0.46 (Cohen, 1988: medium), the magnitude of text + visual (multiple) hypertext gloss combination was moderately effective on L2 vocabulary acquisition when L2 learners were given two conditions: a text-only or a text + visual hypertext glosses. The results revealed that various L2 learners, including English as a second or foreign language (ESL/EFL), Spanish as a foreign language (SFL), Japanese as a foreign language (JFL), and German as a foreign language (GFL), benefit from multiple hypertext glosses while reading computerized texts. In terms of research design, hypertext gloss studies have been almost always conducted in settings of class session-based quasi-experiment design with a researcher-developed program at a university or college level. More implications are discussed for future research. [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.]