Exploring the impact of disability on self-determination measurement

•We studied the impact of the presence of disability in self-determination measurement.•Autonomy dimension is the most influenced by the presence of disability.•This study provides further insight of the self-determination construct as defined through Causal Agency Theory.•Self-determination can be reliably assessed in all youth with the same measure. Self-determination is a psychological construct that applies to both the general population and to individuals with disabilities that can be self-determined with adequate accommodations and opportunities. As the relevance of self-determination-related skills in life has been recently acknowledged, researchers have created a measure to assess self-determination in adolescents and young adults with and without disabilities. The Self-Determination Inventory: Student Report (Spanish interim version) is empirically being validated into Spanish. As this scale is the first assessment addressed to all youth, further exploration of its psychometric properties is required to ensure the reliability of the self-determination measurement and gain further insight into the construct when applied to youth with and without disabilities. More than 600 participants were asked to complete the scale. The impact of disability on the item response distributions across the dimensions of self-determination was explored. Differential item functioning (DIF) was found in only 5 of the scale’s 45 items. Differences primary favored youth without disabilities. The weak presence of DIF across the items supports the instrument’s psychometrical robustness when measuring self-determination in youth with and without disabilities and provides further understanding of the self-determination construct. Implications and future research directions are also discussed.