This study examined the interrelationship between tenth-grade students' problem solving ability (PSA) and their domain-specific knowledge (DSK) as well as reasoning skills (RS) in a secondary school of Taiwan. The PSA test was designed to emphasize students' divergent-thinking ability (DTA) and convergent-thinking ability (CTA) subscales in the area of Earth science. Two hundred and sixty tenth graders who were enrolled in six Earth science classes at a public senior high school located in the eastern region of Taiwan were participants. Major findings are as follows: (a) A significantly positive correlation existed between students' PSA and their DSK and RS, approaching large effect sizes; (b) Both students' DSK and RS significantly explained the variance of their PSA with large effect sizes; (c) Students' RS could more significantly explain the variance of their DTA subscale with medium effect size while DSK might more significantly explain the variance of their CTA, approaching large effect size. The research suggests that more emphasis should be placed on the reasoning skills when developing students' divergent-thinking abilities, while stressing more domain-specific knowledge when students' convergent-thinking ability is considered.