This study investigated the effects of online extensive reading in a syntactically parsed text format compared to regular block format on speed, retention, and proficiency in English reading among Japanese learners of English. A syntactically parsed text format breaks sentences of a text into smaller groups of words or chunks with the intention of increasing the ease of reading. For one academic year, 289 participants at a public university in Japan read English texts of their choosing online in either a parsed format or regular block format. The results showed no significant differences between formats on any of the variables of interest. This suggests that reading in a parsed text format neither hinders nor enhances reading ability or proficiency growth among EFL learners whose first language is linguistically distant from English. Evidence emerged, however, that the reading itself had promoted a significant increase in reading proficiency for both groups.Extensive reading, or the reading of a large quantity of freely chosen texts at or below one's current reading proficiency level, is an effective means of improving English reading proficiency for learners of English as second or foreign language (Nakanishi, 2015). Unfortunately, traditional paper-based extensive reading programs have been difficult to implement in most EFL contexts due to the vast number and variety of reading materials such programs require (Davis, 1995). However, with the steady rise of smartphone and internet use in emerging economies across Asia (Poushter, 2016), extensive reading can now be done online at little or no cost (Lin, 2014), making it a more viable option for a widening range of EFL contexts.At the same time, viewing texts through a browser rather than off of a printed page allows readers to change the font size, page width and other aspects of the text's format. This new level of control over how a text is displayed raises the question of whether texts could be made more readable through systematically altering their format in some way. Indeed, basic changes in font size, white space, and positioning of a digital text can affect reading performance for both native and non-native readers