Studies have shown the potentials of reading on the development of language. Especially, the literature on second language reading is replete with evidence that unearths the incidental acquisition of vocabulary through reading. Free and pleasurable reading, which has a marked effect on the frequency of reading, contributes significantly to the incidental acquisition of vocabulary. However, only a few studies have explored the interconnection among vocabulary acquisition, free and/or pleasure reading, and the reading frequency. To this end, this study manifests the incidental acquisition of vocabulary through reading and foregrounds the importance of free reading, reading pleasure, and reading frequency for vocabulary development. By confirming the strong correlation between reading frequency and the vocabulary test scores of the participants we attest that the reading frequency is significantly associated with free and/or pleasure reading (in our case, liking towards self-selected reading). We also theoretically contextualize and support the argument of incidental vocabulary learning through reading from a biological perspective. Given that the acquisition of any language subskill is enabled by the amalgamation of nature and environment, insights into the biological system of reading implicates a better understanding of the incidental acquisition of vocabulary through reading. [ABSTRACT FROM AUTHOR]