BackgroundStudents with low intellectual functioning (LIF) often experience barriers to participating in social research due to the literacy demands of the survey's typical self-administered format. Although evidence for the validity of the read-aloud format for educational testing abounds, few studies have analyzed the impact of application formats on attitudes or opinion questionnaires for LIF students.AimTo analyze the effect of self-administered vs read-aloud formats on LIF and typical development (TD) students using four psychological questionnaires for school contexts (Student Engagement Instrument, Multidimensional School Engagement Scale [MSES], Brief Multidimensional Student Life Satisfaction Scale, and School Participation Scale).MethodA mixed factorial (2x2) design was used. Thirty-two students participated (14 to 19 years old; M = 15.39; SD = 1.27): 17 with LIF and 15 with TD.ResultsReliability indices between formats for LIF students in most questionnaire subscales were found to be adequate and equivalent. All instrument subscales had appropriate intra-subject correlations between formats, indicating that LIF students had similar scores in both. Only the MSES showed a format effect, where LIF students reported fewer disengagement behaviors in the read-aloud format. Frequentist and Bayesian statistics were conducted looking for convergences due to the small sample size.ConclusionWe discuss the case-related appropriateness of each application format and propose a new criterion to choose between them to guarantee the inclusion of LIF students in psychological research.