The Trends in International Mathematics and Science Study (TIMSS) is one of the most influential assessments of student achievement conducted every four years. It provides reliable data on mathematics and science achievements in grade 4 and grade 8 as well as information about instructional curricular and teaching-learning process. This helps to make decisions on policy development and identify areas of progress. This research delivers evidence on factors that influence the improvement in the scores of TIMSS examination in 2015 compared to 2011 in the Kingdom of Bahrain. Since the Kingdom experienced a major reformation in mathematics and science education, this research analyzes the improvement in students' skills and knowledge by comparing the same cohort results in 2011 and 2015 in mathematics as well as science. This research is also trying to identify other factors, as benchmarked by the Bahrain Numeracy Strategy (BNS) such as school environment, teacher education, teacher's professional development, and classroom contexts for learning and instructional support which backed the improvement. This research provides initiatives to be taken to accomplish TIMSS Center Point 500 in the coming TIMSS examination in 2019 or later.