The Adult Reading History Questionnaire (ARHQ) is one of the most commonly used measures in research on adult dyslexia and family risk. It has been consistently shown that higher scores on ARHQ strongly correlate with adult reading difficulties. However, ARHQ is a lengthy measure (23 items) which reduces its applicability in studies with multiple questionnaires and extensive assessment batteries. In view of this, a recent study by Feng et al. (2020) used a machine learning approach and found that only 6 items from the original ARHQ are sufficient for accurate identification of adult reading difficulties in the US context. In the present study, we aim to validate a brief version in a Finnish and Dutch context. We first identify the items that are most important in a sample of Finnish adults using Exploratory Factor Analysis and Item Response Theory (Sample 1 - Vuokko Study). Further, we aim to validate the brief questionnaire in independent Finnish and Dutch samples (Sample 2 and 3 - JLD and RID Studies). ...