With the advent of new research paradigms and the prevalence of diverse influential factors, the intriguing issue nowadays is to identify what actually determines English as a second language (ESL) learners' reading comprehension. This study examined gender, socioeconomic status (SES), and ethnicity as predictors of ESL learners' reading age and determinants of ESL learners' reading comprehension. We used the Reading Evaluation and Decoding System test to determine participants' reading comprehension. A total of 2,608 university undergraduates of various SES and ethnic groups participated in this study. By conducting linear regression analysis, we determined the role of gender, SES, and ethnicity in predicting learners' reading comprehension. The findings of the current study suggested that gender and SES were not substantial predictors of learners' reading age; however, ethnicity was influential in this regard.