Extensive Reading and Reading Proficiency – What the Evidence Says

Extensive reading (ER) is a practice I learned about as an MA student, but never saw as part of a curriculum in my career. Most research (see references) continues to be published about the benefits of extensive reading. Through my correspondence with other English language program coordinators, I have learned that extensive reading is implemented in some programs, some with great success. With my English language program in the developmental stages, I have found that Jeon & Day’s more recent article (2016) – a meta-analysis on the effectiveness of ER on reading proficiency – to be very helpful in that it provides evidence for the effectiveness of extensive reading on reading proficiency as well as guidelines for implementing an extensive reading program.


Jeon, E-Y. & Day, R.R. (2016). The effectiveness of ER on reading proficiency: A meta-analysis. Reading in a Foreign Language, 28(2), 246-265. Retrieved from http://nflrc.hawaii.edu/rfl/October2016/articles/jeon.pdf.

Introduction, Research Questions, & Literature Review

The article starts by defining extensive reading as “a way of learning a language through a great amount of reading for pleasure,” followed by listing its contribution to various aspects of language proficiency and its effect on the affective domain (p.246). The purpose of the study is to investigate the overall effectiveness of extensive reading, and following questions helped guide this purpose.

  1. What is the overall effectiveness of ER on reading proficiency (reading comprehension, reading rate, and vocabulary) in ESL and EFL settings?
  2. To what extent do identification (year of publication), context (age, ESL and EFL setting, library size), treatment (length, text type, ER form), and outcome (reading comprehension, reading rate, and vocabulary) variables affect the impact of ER?

The authors primarily reviewed three meta-analyses on extensive reading: Krashen’s meta-analysis (2007) on extensive reading on EFL adolescents and young adults, Kim’s (2012) on extensive reading encompassing the cognitive domain and affective domain, and Nakanishi’s (2015) on the overall strength of extensive reading and how its effect differed depending on the participants’ ages and periods of instruction. Jeon and Day (2016) found that each meta-analysis had weaknesses, such as poor design, not enough studies to qualify as a meta-analysis, and the inclusion of studies in non-ESL and non-EFL contexts. The review showed that extensive reading in practice is not exactly the same as it is in theory. It also found gaps in the literature with few or no studies on the implementation of extensive reading, the setting, the size of the library, and the type of texts being used.


To search for the literature, the authors conducted both online and manual bibliographical searches. The study used Day & Bamford’s five characteristics of extensive reading (2002), experimental and quasi-experimental research designs, and publications dates from 1980 to 2014 as their criteria for inclusion. They found 51 samples from 32 studies that were experimental in design and 20 samples from 17 studies that used a pre-test post-test research design.

For coding, the authors used markers to identify the publication of each study, to determine which of their research questions was addressed, and to identify information in the study such as context, treatment, and outcomes. To calculate effect sizes, they used the Comprehensive Meta-Analysis Program (Cohen, 1977).


Publication bias

  • “[T]he results of Fail-test N test revealed that unpublished studies reporting non-significant findings are unlikely to reverse the findings” (p.252)

Overall effectiveness of ER

  • For the experimental studies, the overall effectiveness was 0.57, indicating “the superiority of the ER group over the intensive or traditional reading group on the immediate post-test” (p.253)
  • For the pre-test post-test studies, the overall effectiveness was small to medium (d=0.79)

The moderator analyses

  • The table below shows the results of the moderator analyses for the experimental studies only. The pre-test post-test studies had small numbers of effect sizes. The purpose of the moderator analyses is to assess differences among different variable such as age, text type, or skill focus.

Discussion & Results

Extensive reading has a small to medium effect on reading proficiency, which the authors interpret as “a promising outlook for practicing extensive reading in EFL settings” because most of these studies were in EFL contexts (p.261).

The discussion and results section provided practical guidelines for teachers, administrators, and policy makers, such as

  • Understand that it takes time to see the benefits. Results are not immediate.
  • Implementation is easier when extensive reading is part of the curriculum.
  • Extensive reading programs need systematic support from their schools or governments.
  • Library costs can be alleviated by using computer reader programs, such as Moodle Reader, and using digital texts

This meta-analysis also found that there is a growing interest (such as in my case) and a developing expertise in extensive reading classroom implementation. In terms of students, the analysis found a higher effect with adults and lower effect with adolescents, likely due to cognitive and test-centeredness factors. Additionally, some students may not be ready to read extensively outside the classroom.

Additionally, the presence and size of a library had no significant influence on the impact of the extensive reading programs. Although technology can help reduce library costs, some students may not be comfortable using computer reader programs or digital texts for extensive reading purposes.

Limitations of this study were that most studies investigated extensive reading in Asia Pacific contexts. There was a small number of longitudinal studies, and studies on young learners.


Extensive reading works! This article provides further evidence for me that Richard R. Day is the leading expert in extensive reading in foreign languages. Many of the studies I cite come from the online journal Reading in a Foreign Language of which Dr. Day is co-editor. I encourage teachers and researchers interested in extensive reading to follow Day’s work but to also include research and implementation guidelines from other sources.

The discussion and conclusion section provide a lot of helpful guidelines for schools to develop their extensive reading programs. From a researcher and administrative point of view, I’m interested in future studies that look at:

  • What schools have had success with extensive reading for 10+ years and how do they measure success?
  • What schools have not had success with developing an extensive reading program and why? What were their major issues: logistics, personnel, curriculum, etc?
  • What schools have no (immediate) intention of integrating extensive reading in their curriculum and why?
  • What schools are in the process of redesigning their extensive reading programs?
  • What pedagogical challenges do teachers face in an extensive reading program that the school considers successful?

If you want to learn more about how extensive reading can help improve writing in the contexts of English for Academic Purposes, please read an earlier ELT Research Bite post here: http://www.eltresearchbites.com/201611-integrating-extensive-reading-and-writing/


Cohen, J. (1977). Statistical power analysis for the behavioral sciences (rev. ed.) New York, NY: Academic Press.

Day, R.R. & Bamford, J. (2002). Top ten principles in teaching extensive reading. Reading in a Foreign Language, 14, 136-141.

Haupt, J. (2015). The use of a computer-based reading rate development program on pre-university intermediate level ESL learners’ reading speeds. Reading Matrix: An International Online Journal, 15(1), 1-14.

Jeon, E. & Day, R.R. (2015). The effectiveness of core ER principles. Reading in a Foreign Language, 27(2), 302-307.

Kim, J. (2012). A meta-analysis of extensive reading researches. English Language & Literature Teaching, 18, 85-106.

Komiyama, R. (2013). Factors underlying second language reading motivation of adult EAP students. Reading in a Foreign Language, 25(2), 149-169.

Krashen, S. (2007). Extensive reading in English as a foreign language by adolescents and young adults: a meta-analysis. The International Journal of Foreign Language Teaching, 3, 23-29.

Macalister, J. (2015). Guidelines or commandments? Reconsidering core principles in extensive reading. Reading in a Foreign Language, 27(1), 122-128.

Mori, S. (2015). If you build it, they will come: From a “Field of Dreams” to a more realistic view of extensive reading in an EFL context. Reading in a Foreign Language, 27(1), 129-135.

Nakanishi, T. (2014). A meta-analysis of extensive reading research. TESOL Quarterly, 49(1), 6-37.

Nation, P. (2015). Principles guiding vocabulary learning through extensive reading. Reading in a Foreign Language, 27(1), 136-145.

Peel, M. (2015). Implementing an extensive reading program in an intensive university EAP curriculum. MA TESOL Collection, SIT Digital Collections. Paper 706.

Robb, T. & Kano, M. (2013). Effective extensive reading outside the classroom: A large-scale experiment. Reading in a Foreign Language, 25(2), 234-247.

Sakurai, N. (2015). The influence of translation on reading amount, proficiency, and speed in extensive reading. Reading in a Foreign Language, 27(1), 96-112.

Sampson, N.E. (2013). An extensive reading approach to teaching English second language reading comprehension with the American Language Institute at the University of Toledo. Theses and Dissertations, The University of Toledo, Paper 194.

Stoller, F.L. (2015). Viewing extensive reading from different vantage points. Reading in a Foreign Language, 27(1), 152-159.

Tien, C. (2015). A large-scale study on extensive reading program for non-English majors: factors and attitudes. International Journal of Applied Linguistics & English Literature, 4(4)

Waring, R. & McLean, S. (2015). Exploration of the core and variable dimensions of extensive reading research and pedagogy. Reading in a Foreign Language, 27(1), 160-167.

Webb, S. & Chang, A.C.-S. (2015) How does prior word knowledge affect vocabulary learning progress in an extensive reading program? Studies in Second Language Acquisition, 36, 651-675.

Yamashita, J. (2015). In search of the nature of extensive reading in L2: Cognitive, affective, and pedagogical perspectives. Reading in a Foreign Language, 27(1), 168-181.

Featured photo by DGlodowska

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Jeremy Slagoski
Jeremy earned his PhD in Teaching & Learning (Foreign Language & ESL Education) at the University of Iowa. He's currently working on ELT research projects on extensive reading, professional learning, social media, and teacher cognition. He lives in Carbondale, Illinois with his wife, daughter, and cat.