The Defining Issues Test (DIT) has been widely used in psychological experiments to assess one’s developmental level of moral reasoning in terms of postconventional reasoning. However, there have been concerns regarding whether the tool is biased across people with different genders and political and religious views. To address the limitations, in the present study, I tested the validity of the brief version of the test, that is, the behavioral DIT, in terms of the measurement invariance and differential item functioning (DIF). I could not find any significant non-invariance at the test level or any item demonstrating practically significant DIF at the item level. The findings indicate that neither the test nor any of its items showed a significant bias toward any particular group. As a result, the collected validity evidence supports the use of test scores across different groups, enabling researchers who intend to examine participants’ moral reasoning development across heterogeneous groups to draw conclusions based on the scores.
