Abstarct: This study presents a quantitative evaluation of English for Specific Purposes (ESP) program effectiveness within the context of Iraqi higher education. As English proficiency becomes increasingly critical for academic and professional success in non-English speaking countries, understanding the efficacy of specialized language instruction is paramount. This research employed an ex post facto comparative design to assess differences in ESP outcomes across academic disciplines (Medicine, Engineering, and Business) and institutional types (public vs. private universities). Data were collected from 200 undergraduate students using an ESP proficiency test and a questionnaire measuring perceptions of curriculum relevance, teaching effectiveness, and program satisfaction. The findings revealed significant disparities in program efficacy. Students in medical and engineering disciplines, as well as those enrolled in private universities, demonstrated significantly higher ESP proficiency and reported more positive perceptions of their programs compared to their counterparts in business and public institutions. Furthermore, a moderately strong positive correlation (r = 0.62) was found between students' proficiency levels and their perceived program effectiveness, underscoring the strong lixnk between well-aligned curriculum, quality instruction, and positive learning outcomes. The study concludes that while ESP programs in Iraq contribute to field-specific language development, their effectiveness is inconsistent and heavily influenced by curricular design, teacher quality, and institutional resources. These findings highlight an urgent need for standardized, needs-baxsed curriculum reforms, enhanced teacher training, and equitable resource allocation to ensure that ESP programs adequately prepare Iraqi graduates for the linguistic demands of the globalized workforce and further academic pursuits.