Before the Global Financial Crisis hit the region in 2008 the buoyant construction activities in the United Arab Emirates, and especially in Dubai, was successful in attracting many multinational companies and professionals from across the globe. One of the main drawbacks of this business environment is the increasingly high competition between such companies to recruit and retain the needed human resources. This paper has investigated the cultural diversity phenomenon in construction project teamss in Dubai and its affect on their effectiveness. The main objective of the paper is to examine the impact of cultural diversity of the project team on their performance. The paper reports the results of an empirical study into the relationship between the extent of cultural diversity and project team performance.The findings of the empirical study suggest that there is no significant relationship between the degree of project team cultural diversity and their overall performance measure. However, the results showed that there is a negative relationship between the degree of cultural diversity and output, productivity, and efficiency.