Identifying key determinants of success plays an important role in efforts of assessing the current state of educational practices and implementing effective actions to improve academic performance. Given how important is accurate identification of these determinants for valid comparisons, the aim of this research was to present extensive comparative results on 8th grade students' science success for 39 countries. To this end, a total number of 229,493 students' information obtained from the last cycle of Trends in International Mathematics and Science Study was handled. Unlike previous studies in which success has been tried to be explained with some factors, this research extended the literature by investigating the effective factors as well as gender-related variability on science success with a holistic view. Using heterogeneous choice models, unobserved heterogeneity caused by gender difference was tested and controlled. The findings showed that gender variability was evident for 10 countries. Furthermore, factors associated with students' future educational goals, home educational resources and confidence were found as the common determinators of science success in all participant countries. Another notable finding was all factors, except time spent on doing homework, tended to differentiate the success status between girls and boys of 22 countries.