This study explored the predictive effects of science self-beliefs on science achievement for 24,680 13-year-old students from Gulf Cooperation Council member countries--Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates--who participated in the Trends in International Mathematics and Science Study (TIMSS) 2007. The performance of adolescent students in Qatar and Saudi Arabia on the TIMSS 2007 science assessment was significantly below the TIMSS scale average. Adolescent students' science beliefs had both positive and negative predictive effects on science achievement across the Gulf Cooperation Council member countries. (Contains 2 tables.)