The thesis attempts to highlight the intellectual difference between bilingual and monolingual individuals. It consists of two main parts: (1) a literature review defining bilingualism, the brief history of the research studies, facts supporting bilingual comprehensive intelligence; (2) a practical section with a small-scale research study. In the first section, after defining some basic terms about bilingualism and its’ various types, there is a detailed description regarding research studies from various perspectives and times to introduce the reader to the theoretical field of bilingualism. The second section contains empirical research based on studies discussed in the first part, and an IQ test. Ianco-Worrall’s Symbol Substitution Task (See Appendix 2) is made by an 8-year-old bilingual and monolingual child to survey whether bilinguals are able to analyze language as an abstract system earlier than monolinguals. The test proves the statement, because the monolingual child fails over the bilingual. An IQ test, called Raven’s Progressive Matrices (See Appendix 3), measures bilingual and monolingual individuals results on nonverbal tests to compare their intelligence difference. The results support the statement again, because bilinguals accomplished better than monolinguals. Furthermore, a case study with the 8-year-old bilingual child support the idea that bilingualism provides greater benefits for intellectual growth. The thesis was conceived of and realized in the hope of highlighting the intellectual difference between bilingual and monolingual people.