Although fairness in assessment practices has gained noticeable attention over the recent years, there has been a long-lasting study to design and validate a questionnaire to measure it from a psychometric perspective. Thus, this study aims to develop and validate a questionnaire with adequate psychometric properties to measure fairness in classroom assessment. Using a random sampling method, two samples of male and female university students for the first pilot (n = 128) and the second pilot (n = 360) were selected from Ayatollah Borujerdi University and Lorestan University. Drawing on the past literature, a pool of items (n = 118) were extracted and subjected to a 12-step systematic procedure, including content analysis and sampling; creating an item bank; running the first pilot; creating item pool one; expert judgment to evaluate the sub-scales; running an interview and think-aloud protocol; running Cronbach's alpha; running the second pilot; running exploratory factor analysis, confirmatory factor analysis, and Cronbach's alpha; creating item pool two; expert review; and translation and translation quality check. Findings yielded a 110-item questionnaire with 10 sub-scales: learning materials and practices (18 items); test design (24 items); opportunities to demonstrate learning (8 items); test administration (21 items); grading (11 items); offering feedback (6 items); tests results interpretation (5 items); decisions based on tests results (3 items); test results consequences (4 items); and students' fairness-related beliefs and attitudes (10 items). The hope is that this questionnaire can serve research and educational purposes.