This study aims at testing the generalisability of Marsh’s Internal/External (I/E) frame of reference model as well as its Dimensional Comparison Theory (DCT) extension in a sample of United Arab Emirates (UAE) high school students. Relationship between self-concept and achievement in Arabic, English and mathematics were explored. A sample of 990 students (532 girls; age 13–20) participated in this research. Arabic, English and maths self-concepts from the Self-Description Questionnaire were used. Results revealed positive paths between the same domains for achievement and self-concept and negative paths cross-domains. Significant negative paths were also found between English and Arabic, suggesting that languages sharing the same alphabet/characters could belong to the same ‘family’ and be considered as a near path, while languages from different families could be a far path. Differences in achievement were in favour of girls, although boys presented higher maths self-concept.