The fact that the absolute is only God, and therefore, God is the first to come to mind when perfection is mentioned, is a common occurrence among believers. Perfectionism was also associated with God by the early personality theorists, moved away from its religious meaning over time, and its relationship with piety was little taken into account until recently. The fact that perfectionism, which has a religious motif in its essence, came to life in the field of religious sciences in general and psychology of religion in particular, in other words, bringing the concept of religious perfectionism into the literature became possible by a limited number of measurement attempts made after 2010. In this study, which we carried out to contribute to the concept of religious perfectionism in the Turkish literature, religious perfectionism, which is based on setting high standards for religious life, was discussed as a whole with order, discipline, inadequacy of one's self, perfect religious expectations and generalizations about others. Our study aims to fill the gap in the relevant literature by making the operational definition of religious perfectionism, as well as measuring it. After determining the need for scale development and literature review, multidimensional perfectionism scales were reviewed and an item pool was created. Some features of perfectionism, such as discipline, generalization, and performance control, which are not dimensioned in multidimensional scales, were also adapted to piety. Previously developed religious perfectionism scales were also examined and, unlike them, we attempted to emphasize both the individual's religious life and the perfect God perception. The opinions of five experts in the field of Psychology of Religion were consulted about the adequacy of the items, so the first form of the scale was prepared for the pilot scheme. The study group of the study consists of 610 Muslim participants who live in Turkey, believe in Allah (God) and regularly perform at least one worship. A total of 254 people, 192 (75.6%) of whom were female and 62 (24.4%) were male, participated in the pilot scheme. A total of 356 participants, 242 (68%) of whom were women and 114 (32%) were men, participated in the main study. The educational background of the participants was undergraduate or postgraduate, and the majority of them were between the ages of 18-30. In order to determine the validity of the scale, construct validity and criterion-related validity were examined. Explanatory Factor Analysis (n=254) and Confirmatory Factor Analysis (n=356) were used for construct validity and correlation analysis was performed for criterion-related validity. In addition, the differences between the item mean scores of the lower 27% and upper 27% groups were tested with the unrelated T-test for item discrimination. The reliability of the scale was determined by Cronbach's Alpha (a) and test-retest methods. As a result of Explanatory Factor Analysis, the scale was divided into two factors as Positive Religious perfectionism and Negative Religious perfectionism, as designed. The positive dimension of the scale included items that included the very high standards that the person set about God and his religious life, the order and discipline shown in worship. In the negative dimension of the scale, items such as finding the worships inadequate, doubting the actions and worrying about making mistakes, as well as the general acceptances that the individual has about himself, God or others, were included. The total score of the dimensions showed the general religious perfectionism level, and as the score gets higher, so does the religious perfectionism level. The scale can be used to measure the general religious perfectionism level based on the total score in the studies to be carried out, or it can also be used by dividing it into its positive and negative factors. The internal consistency coefficient of Positive Religious perfectionism was 0.913; it was 0.876 for Negative Religious perfectionism, and the overall reliability for the 22-item structure of the scale was 0.904. As a result of the test-retest performed with a new study group of 95 people with an interval of 14 days, a positive significant correlation was found between the pretest and retest levels (r=0.960 p