The chapter provides an overview of the TIMSS 2015 international results in mathematics, focusing on fourth-grade students. TIMSS 2015, conducted by the IEA and Boston College, assessed mathematics and science at the fourth and eighth grades, with a special advanced assessment for secondary school students. The study involved 57 countries and 7 benchmarking entities, with over 580,000 students participating. The assessments were based on comprehensive frameworks and included nearly 800 items, emphasizing students' application and reasoning skills. New features included a home questionnaire completed by parents or caregivers. The results highlight trends in achievement, with East Asian countries leading in mathematics, and show improvements in many countries over time. The chapter also discusses gender differences in achievement, the impact of home environment on learning, and the importance of early literacy and numeracy activities.The chapter provides an overview of the TIMSS 2015 international results in mathematics, focusing on fourth-grade students. TIMSS 2015, conducted by the IEA and Boston College, assessed mathematics and science at the fourth and eighth grades, with a special advanced assessment for secondary school students. The study involved 57 countries and 7 benchmarking entities, with over 580,000 students participating. The assessments were based on comprehensive frameworks and included nearly 800 items, emphasizing students' application and reasoning skills. New features included a home questionnaire completed by parents or caregivers. The results highlight trends in achievement, with East Asian countries leading in mathematics, and show improvements in many countries over time. The chapter also discusses gender differences in achievement, the impact of home environment on learning, and the importance of early literacy and numeracy activities.