Preschool-aged children continually learn new skills and perfect existing ones. "Mastery motivation" is theorized to be a personality trait linked to skill learning. The Dimensions of Mastery Questionnaire (DMQ) quantifies mastery motivation. This pilot study evaluated DMQ test-retest score reliability (preschool-version) and included exploratory analysis of test-retest score reliability with a subgroup of children with a physical disability. The child's parent completed the DMQ twice (30-day mean retest interval) and rated DMQ for ease of use. Test-retest score reliability was estimated for DMQ Total, aspect and scale scores using intraclass correlation coefficients (ICCs). Thirty-three mothers participated (children's mean age = 4 years 1 month, SD = 1 year 2 months). Total score and expressive aspect test-retest score reliability were good (ICCs 0.76 and 0.70, respectively) and instrumental aspect test-retest score reliability was excellent (ICC = 0.87). Five of the 7 scales had ICCs greater than 0.74. The mastery pleasure scale scored lowest in test-retest score reliability (ICC = 0.35). Total score test-retest reliability was good for children who have a disability (n = 12) and in children typically developing (n = 21): ICCs 0.71 and 0.79, respectively. The DMQ was found to be easy to complete using a 5-point scale with "1" being "very difficult" and "5" being "very easy." The mothers' mean score was 4.4/5.