Numerous studies have attributed gender difference in mathematics achievement to various sociocultural influences. Singapore is a country of higher gender equality as represented in the Global Gender Gap Index and Singaporean girls perform as well or higher than boys in international mathematics assessments. This study develops a conceptual model to examine the relationship and effects of parental involvement in education, teacher efficacy, and students’ attitudes towards mathematics on mathematics achievement for Singaporean eighth grade students using Trends in International Mathematics and Science Study (TIMSS) 2011 data. The study finds that there is no significant gender difference in parental involvement in education and teacher efficacy and there is no gender difference in the attitude of like learning mathematics among Singaporean eighth grade students. The attitude of confidence in mathematics has positive and significant effect on mathematics achievement and the effect is greater for girls than boys. Parental involvement in education and teacher efficacy were found to have greater effect on girls’ confidence in mathematics than on boys’. As such, increasing involvement in mathematics education and providing positive reinforcement to raise girls’ self-confidence in mathematics by parents and teachers should be an integral part of any initiative to reduce gender gap in mathematics achievement.