We examined the construct validity and reliability of the previously developed Psychological and Social modules of the Portuguese Physical Literacy Assessment Questionnaire (PPLA-Q) using Mokken Scale Analysis in a sample of 508 Portuguese adolescents in public schools in Lisbon. We used a retest subsample (n = 73) to calculate the Intraclass Correlation Coefficient. Eight PPLA-Q scales can be interpreted as moderate-to-strong Mokken scales (H = .47-.66) with good total-score reliability (¿ = .83-.94), and moderate-to-excellent test-retest reliability (ICC95%CI = .51-.95); four scales had an interpretable invariant item ordering. All but the Physical Regulation scale functioned similarly across sex. Scale-scores correlated as expected, with low-to-moderate correlations across domains supporting convergent and discriminant validity. These results support the construct validity and reliability of the PPLA-Q to assess the psychological and social domains of physical literacy in Portuguese adolescents (15-18 years) enrolled in physical education.