Numerous studies have been conducted to prove the efficacy of extensive reading (ER). The majority of them have revealed the impact of ER on receptive skills. How can ER affect productive skills? This presentation explores what aspects of ER could possibly influence the acquisition and retention of controlled productive vocabulary. Sixty-two English majors at a private university in Japan who experienced ER for 13 months participated in the study. They took the Productive Vocabulary Levels Test at the 2,000-word level 3 times: at the start of ER, toward the end of the second semester, and in the beginning of the third semester following the school closure due to the COVID-19 pandemic. The findings from statistical tests and analyses of the participants’ reading records will be discussed. Pedagogical suggestions will be offered to conclude the presentation.