The purpose of this research is to examine the impact of Achievement Goal Motivation Theory on students’expectancies for success, beliefs about ability, usefulness, importance and interest for the mathematics subject.Research asserts that possessing mastery-learning- oriented motivation has a more positive impact on students’expectancies for success, beliefs about ability, usefulness, importance and interest for mathematics. This researchapplies a quantitative method of study. Quantitative data have been analysed using Wigfield and Eccles’sExpectancy–Value Theory Achievement Questionnaire in order to assess student’s expectancies for success, abilitybeliefs and subjective task values. In the case study of a private Suleyman Sah University, Turkey, the focus of thequestionnaire has been derived from the central research question: How applications of Achievement Goal Theoryaffect students’ expectancies for success, beliefs about ability, usefulness, importance and interest for mathematics?The questionnaire was given to 40 students who were selected randomly in mathematics class. Also, in order toidentify students’ goal orientation, Elliot’s AGQ (Achievement Goal Questionnaire) was applied to those students.Their Achievement Goal motivation types were compared to their beliefs about ability, usefulness, importance andinterest for mathematics. Based on the quantitative data analysis, it was concluded that students with masterylearninggoal orientation have more expectancies for success, for them mathematics is a more useful and importantsubject, and, most importantly, they show more interest for the subject. These are very important components tobe persistent in the face of difficulties and obstacles on the way to achievement in teaching mathematics.