The purpose of this study was to understand the relationship between critical and creative thinking skills and learning achievement of senior high school and university students of both genders. The sample consisted of 85 senior high school and 90 university students drawn using cluster random sampling. Senior high school level samples were drawn from senior high schools in the city of Tebing Tinggi, while university level samples were drawn from the Jember state Islamic institute. Regression analysis was applied to understand the correlations among educational level and gender differences in the relationship between critical and creative thinking skills and learning achievement. The results show that senior high school and university students' critical thinking skills correlated positively with both creative thinking skills and learning achievement for both genders. Furthermore, senior high school and university students' creative thinking skills show significantly positive relationships with learning achievement in both sexes.