Psychometric properties for a new instrument, the EZ-Personality Questionnaire designed to assess the functioning of students with cultural-familial mental retardation, are presented. The analysis of data from 661 participants yielded a 37-item, seven-scale instrument that confirmed the five hypothesized factors of Positive Reaction Tendency, Negative Reaction Tendency, Effectance Motivation, Expectancy of Success, and Outerdirectedness and identified two additional factors of Curiosity/Creativity and Obedience. Separate studies were conducted to establish the concurrent and construct validity of the instrument. Reliability was examined through split-half and test-retest analyses. All psychometric indices were within acceptable levels, resulting in an instrument with potential applications in research, education, and clinical settings.