Abstarct: Language proficiency is a key indicator of academic readiness and future opportunities for students. In Mosul high schools, audio-visual (AV) infrastructure – including projectors, audio systems, multimedia tools, and language laboratories – varies considerably due to post-conflict reconstruction challenges and unequal resource distribution. This ex post facto study compared language proficiency between students attending high-AV-infrastructure schools and those attending low-AV- infrastructure schools in Mosul, Iraq. The study addressed two research questions: (a) whether there is an unadjusted difference in mean language proficiency between the two groups, and (b) whether there is an adjusted difference after controlling for school type (public vs. private) and school location (urban vs. rural). Quantitative data were collected from 240 students across 12 high schools using an AV infrastructure checklist (10 items, 0-20 scale) and existing language proficiency records (listening, speaking, reading, writing composite scores, 0-100 scale). Descxriptive statistics, independent-samples t-test, and one-way analysis of covariance (ANCOVA) were used to analyze differences between groups. Descxriptive findings revealed substantial variation in AV infrastructure across schools (M = 5.32, SD = 2.87, observed range = 0.16 to 9.13). Overall language proficiency was moderate (M = 57.92, SD = 9.74), with receptive skills slightly outperforming productive skills. For Research Question 1, the t-test revealed a statistically significant difference in mean language proficiency between high-infrastructure (M = 68.45, SD = 8.23) and low-infrastructure (M = 47.38, SD = 7.89) schools, t(238) = 8.42, p < .001, Cohen's d = 1.34. For Research Question 2, the ANCOVA revealed a statistically significant difference in adjusted mean language proficiency after controlling for school type and school location, F(1, 236) = 72.45, p < .001, partial η² = 0.24. Both covariates were also statistically significant (school type: partial η² = 0.06; school location: partial η² = 0.04). The findings provide context-specific evidence of an association between school AV infrastructure and language proficiency in a post-conflict setting. The results may inform policymakers, school administrators, and education planners about observed proficiency differences across infrastructure levels. Due to the ex post facto design, causal claims cannot be made.