Introduction As Skinner, Kindermann, Connell and Wellborn (2009) believe, academic engagement is one of the main predictors of academic achievement, and it is quite significant the extent to which learners are interested in and committed to their academic activities and how well they are engaged in learning their various courses. In another definition of academic engagement, Schechty (2005) believes that students’ engagement in the school assignments means that assignments should attract the students so that thay gathers all their energy to accomplish the assignment and sustain their energy to the end of the task. Academic engagement is influenced by various factors such as cognition, classroom structure, learners' ability, teacher training, and environmental conditions (Covington, 1999). It seems one of the effective motivational factors on academic engagement is achievement goal. Pintrich (2000) states that the learners’ attempts to do their assignment are influenced by the goals they select for their education and for accomplishing the assignment. In this regard, the achievement goals theory proposes a framework for understanding the reasons why people display certain achievement behaviors (Barron, Evans, Baranik, Serpell & Buvinger, 2006). Another potentially influential factor on academic engagement is teacher’ feedback. Providing proper feedback by teachers helps the students to identify the main reasons for their success and failure. On the other hand, students use their intrinsic statement and thoughts, referred to as self-talk, when they engage in their academic activities. Depending on their age and position, such self-talks may be long or short, and may involve lips movements, or might be just in the form of a mind-passing thought. One of these self-talks is motivational self-talk. According to McCann and Garcia (1999), motivational self-talk increases the individual’ s attempt and resistance in obtaining their goals. Motivational goals policies focus on adjusting the motivational beliefs and include the student’ s attempt to remember the reason for completing assignments and ensure they have the abilities to accomplish the assignment successfully (Wolters & Benzon, 2013). Therefore, it seems the motivational self-talk is related to academic engagement. Hypotheses 1. Aspects of achievement goals predict the students' academic engagement. 2. Dimensions of teacher feedback predict the students' academic engagement. 3. Motivational self-talk mediates the relationship between achievement goals, teacher feedback, and academic engagement. Method The study adopted a descriptive (correlational) design. It examined the relationships between the research variables as a model. The aspects of the achievement goals and teacher feedback functioned as the independent variables, motivational self-talk was the mediator variable, and academic engagement served as the dependent variable in the model. The statistical population of this research included all female and male high school students (grades 10-12) in 2017-2018 academic year in Yazd (N = 15000). Cochran formula was used to determine the number of participants in the sample group. Accordingly, 400 students (211 females and 189 males) were selected through multistage cluster random sampling method so that district 2 from the two districts, and 3 schools out of all schools of this district, and 15 classes of these schools were randomly selected. The learners in the selected classes were provided with a consent letter and were allowed the opportunity to decide whether or not they wanted to participate in the research. Using the information about their latest classes, the participants filled in paper-and-pencil questionnaires related to the specified variables in the study. Results The results of structural equation modeling (SEM) suggested that, of the various dimensions of achievement goals, mastery goals positively predicted academic engagement both directly and indirectly, through the mediation of motivational self-talk. Performance approach goals, on the other hand, had a positive but indirect correlation with academic engagement. Nevertheless, no significant relationship was found between performance avoidance goals and academic engagement. The findings, on the other hand, revealed that the various dimensions of teacher feedback positively predicted academic engagement both directly and indirectly through the mediation of motivational self-talk. Discussion The results of data analysis using SEM showed that mastery goals can predict academic engagement both directly and indirectly. It can be claimed that students with mastery goals greatly respect understanding and seek learning even when they have a poor performance. On the other hand, the orientation of these goals guides the students’ self-talk toward mastery self-talk that is one aspect of the motivational self-talk. In addition, students with mastery goals emphasized trying more with perseverance to achieve their goals and succeed in their academic assignments using mastery self-talk. In addition, the obtained results from data analysis using SEM indicated that performance-approach goals indirectly predict academic engagement. Students with performance-approach goals more emphasize extrinsic goals while comparing their performance to that of others. Thus, the students’ learning activities and their engagement in academic assignments are determined by their extrinsic and relative ability self-talks in which they remind themselves respectively of the importance of getting good marks, the teacher’ s confirmation, and their peers’ acceptance, and of the importance of putting in a performance that is superior to that of their classmates. The findings further revealed that positive feedback can predict academic engagement both directly and indirectly. The direct effect indicates that positive feedback enhances the students’ academic performance. The indirect effect, on the other hand, can be explained as “ when a teacher has a positive feedback to the student, his/her feedback shows how much the student has approached the pre-determined goals and what gaps must be filled. Another finding of the present research was that negative feedback predicts academic engagement directly and indirectly. Students become disappointed when they receive the negative feedback from their teachers and gradually feel that do not have any control on their performance. Moreover, students make this feedback intrinsic. Therefore, through this negative self-talk, they make a negative perception about themselves and their attempts, which correspondingly brings emotions of shamefulness, humiliation, reject, and demoralization and thus reduces their academic engagement.