Determinants of educational achievement extend beyond the school environment to include the home environment. Both environments provide tangible and intangible resources to students that can influence science achievement. South Africa provides a context where inequalities in socio-economic status are vast, thus the environments from whence students draw resources vary. This paper investigates school and home environments to determine what resources influenced science achievement. Multiple regression analyses were conducted on data from 11,969 South African Grade Nine students, who participated in the Trends in International Mathematics and Science Study in 2011. The findings reveal that both the school and home environments play important roles in students’ science achievement, with the strongest associations exhibited with: speaking the language of the test at home, home assets, and the condition of school buildings. Implications for policy are discussed.