Self-efficacy and achievement goals represent two extensively researched motivational factors in education and have been related to numerous academic outcomes. However, little is known about how they relate to different types of problem-solving. Furthermore, while prior work has found these motivational factors are related, less work has examined them over time, during learning, and controlling for prior knowledge. The current study investigated the relations between these motivational constructs and procedural and conceptual problem-solving in middle school science. Sixth-grade science students' self-efficacy and achievement goals were surveyed along with procedural and conceptual problem-solving before and after instruction. Results revealed students' self-efficacy was positively correlated with both procedural and conceptual posttest performance. However, controlling for prior knowledge, self-efficacy only predicted conceptual performance. No relations were found between achievement goals and procedural or conceptual problem-solving. Additionally, results found that changes in mastery-approach goals were positively related to changes in self-efficacy beliefs.