The aim of this study was to develop "Classroom Assessment Beliefs Scale" (CABS) to determine teachers' assessment beliefs for the classroom. The sample of the study consisted of teachers (n = 440) working in primary schools, middle schools, and high schools in the Central Anatolia Region of Turkey. At the end of the analysis, a 22-item scale with two factors was obtained. The scale consisted of "traditional assessment belief" (TAB) and "alternative assessment belief" (AAB) factors. The explained total variance of the two-factor structure of the scale was 27.854%. The fit indices of the scale were examined, and the model was confirmed to having a good fit (X[superscript 2]/d"f" = 1.85; RMSEA = 0.06; CFI = 0.91; TLI = 0.91; IFI = 0.91). Cronbach's alpha reliability value of the scale was 0.92 for TAB and 0.91 for AAB of the CABS. The developed scale is a psychometrically appropriate instrument to reveal classroom assessment beliefs adopted by teachers.