Abstarct: The purpose of this ex post facto (causal-comparative) study was to determine whether significant differences exist in reading comprehension and vocabulary size between Iraqi university students who had high access to English-related extracurricular activities in high school and those who had low or no such access. The independent variable was the level of access to extracurricular activities during high school (high access vs. low/no access). The dependent variables were reading comprehension scores and vocabulary size scores measured at the university level. The accessible population consisted of first- and second-year students at public universities in Baghdad. Using a two-stage cluster random sampling procedure, four universities were randomly selected from Baghdad, and from each university, one intact class of first- or second-year students was randomly selected. All students in these intact classes were invited to participate (N = 140). baxsed on their retrospective responses to the Extracurricular Activity Access Questionnaire, participants were assigned to either a high-access group (n = 63) or a low/no-access group (n = 77). Reading comprehension was measured using a standardized EFL reading test, and vocabulary size was assessed using Nation's Vocabulary Size Test adapted for EFL learners. Independent samples t-tests were used to compare group means, and effect sizes (Cohen's d) were calculated. Results indicated that the high-access group scored significantly higher than the low/no-access group on both reading comprehension (M = 37.33, SD = 4.52 vs. M = 29.96, SD = 5.63; t[138] = 8.41, p < .001, d = 1.43) and vocabulary size (M = 70.97, SD = 9.82 vs. M = 57.31, SD = 10.75; t[138] = 7.78, p < .001, d = 1.32). Both effect sizes were large. These findings indicate that differential access to English-related extracurricular activities in high school is associated with significant differences in reading comprehension and vocabulary size among Baghdad university students. The study does not claim causation but rather identifies group differences that warrant further investigation.