The aim of the present study was to examine the relationship between learner factors and critical reading ability. The participants of the study were fifty Iranian EFL learners. They answered to a questionnaire on critical thinking ability and took a critical reading test. Their scores were compared and contrasted with regard to the three variables under investigation, namely, proficiency level, gender, and topic knowledge. The results of the study revealed that while proficiency level has a positive effect on the enhancement of critical reading ability of the learners, gender and topic knowledge do not have a significant contribution to the development of this skill. The findings suggested important implications for EFL teachers and materials developers.