Background: Numerous studies have been conducted to investigate the factors related to science achievement. In these studies, the classroom goal structure perceptions, engagement, and self-efficacy of the students have emerged as important factors to be examined in relation to students' science achievement. Purpose: This study examines the relationships between classroom goal structure perception variables (motivating tasks, autonomy support, and mastery evaluation), engagement (behavioral, emotional, cognitive, and agentic engagement), self-efficacy, and science achievement. Sample: The study participants included 744 seventh-grade students from 9 public schools in two districts of Gaziantep in Turkey. Design and methods: Data were collected through the administration of four instruments: Survey of Classroom Goals Structures, Engagement Questionnaire, Motivated Strategies for Learning Questionnaire, and Science Achievement Test. The obtained data were subjected to path analysis to test the proposed model. Results: Students' perceptions of classroom goal structures (i.e. motivating tasks, autonomy support, and mastery evaluation) were found to be significant predictors of their self-efficacy. Autonomy support was observed to be positively linked to all aspects of engagement, while motivating tasks were found to be related only to cognitive engagement. In addition, mastery evaluation was shown to be positively linked to engagement variables, except for cognitive engagement, and self-efficacy and engagement (i.e. behavioral, emotional, and cognitive engagement) were observed to be significant predictors of science achievement. Finally, results revealed reciprocal relations among engagement variables, except for agentic engagement. Conclusions: Students who perceive mastery goal structures tend to show higher levels of engagement and self-efficacy in science classes. The study found that students who have high self-efficacy and who are behaviorally, emotionally, and cognitively engaged are more successful in science classes. Accordingly, it is recommended that science teachers utilize inquiry-based and hands-on science activities in science classes and focus on the personal improvement of the students. Furthermore, it is also recommended that they provide students with opportunities to make their own choices and decisions and to control their own actions in science classes.