International student assessments are used to measure the education system quality in many countries including the United Arab Emirates (UAE). However, student performances in these exams are influenced by a complex array of factors. This study collected interview data from six central officials, three school principals and vice principals, and 12 teachers and subject coordinators in the UAE and found that language and curriculum-related issues were adversely affecting student performances in the Trends in International Mathematics and Science Study (TIMSS) and Program for International Student Assessment (PISA) exams. The student understanding of the content in the exams was connected to their language abilities, and the lack of student ability to apply mathematics and science knowledge was owing to the modular-based curriculum and pedagogical methods used in the UAE. Therefore, UAE educational decision makers need to deal with these language and curriculum-related issues because they will continue to affect UAE student achievements, the country's international exam rankings, and the overall quality of the education system.