Extensive reading (ER) has been widely recognized for its impact on vocabulary acquisition, yet its role in shaping L2 learners’ affective learning experience remains underexplored. In the early 20th century, Palmer proposed ER (see Day & Bamford, 1998) to lead to enhanced reading abilities and motivate L2 learners to read. Although ER’s potential in language development has been widely studied, few empirical studies have examined this connection within the framework of L2MSS. Selecting Dörnyei’s (2005, 2009) L2 Motivational Self-system (henceforth, L2MSS) which links learners’ future self-concept to their motivation and learning behaviors as our theoretical framework, we measured offline ER’s influence on not only Iranian EFL learners’ vocabulary development but also on their L2 learning experience. In so doing, we selected an experimental group (EG) ( N =32) and a control group (CG) ( N =28) from two university-level intact classrooms who were passing their General English course. The experimental group (EG, N=32) read three proficiency-matched graded readers over an 8-week period, while the control group (CG, N=28) used only the coursebook, Select Readings: Pre-Intermediate . The graded readers were selected in such a way to match learners’ current language proficiency as determined by an Oxford and Cambridge Quick Placement Test (OCQPT). Our participants’ baseline vocabulary knowledge was assessed using a teacher-made test, while their baseline L2 learning experience was measured through Li’s (2025) L2 Learning Experience Scale measuring six subcomponents: positive emotion, negative emotion, engagement, relationship, meaning, and accomplishment. The findings showed that both groups had little knowledge of the target words before the treatment. However, post-treatment results showed that the EG significantly outperformed the CG in vocabulary knowledge and reported greater gains across multiple L2 learning experience subscales. These findings have important implications for integrating extensive reading into general English curricula to foster both lexical growth and learner motivation.
