This study was aimed to develop an instrument to measure primary and secondary school students' attitudes toward mathematics and to find the underlying dimensions that comprise the attitudes toward mathematics. In addition, it was aimed to examine students' attitudes towards mathematics in terms of gender and grade level variables. For this purpose, a five-point Likert-type instrument consisting of 27 items to measure students' attitudes towards mathematics was prepared and applied. The validity and reliability of the instrument were made on the data obtained from 328 students selected by random sampling method among primary and secondary school students. As a result of the factor analysis performed to determine the construct validity of the instrument, it was seen that the factor loads of the scale items ranged from 0.44 to 0.75, the Kaiser-Meyer Olkin (KMO) value was .89, and the internal consistency coefficient (Cronbach alpha) value calculated for the reliability study was α=.88. In addition, principal components factor analysis with varimax (orthogonal) rotation applied to find the sub-dimensions of the instrument revealed five factors: (1) in-class; (2) the nature of mathematics; (3) problem solving; (4) understanding and (5) self-efficacy. Findings related to validity and reliability studies show that the instrument has a valid and reliable structure. In addition, as a result of the application of the instrument, it was concluded that the mathematics attitudes of the students did not differ according to gender, but there was a significant difference in terms of grade level. [ABSTRACT FROM AUTHOR]