Instruments to measure self-determination have only been available in the Spanish language to date, for adolescents with intellectual disability (ID). However, given the development of a new measure of self-determination for youth with and without disabilities, the Self-Determination Inventory, there is a need to adapt and validate this tool in the Spanish language so as to provide practitioners with a psychometrically strong measure of self-determination. This study provides evidence of reliability and validity of the Spanish version of the scale, empirically tested with a sample of 620 youth with and without disabilities in Spain. Specifically, validity was evidenced through structural equation modeling approaches, confirming the instrument adequacy to measure self-determination in Spanish speaking youth. Future lines of research are suggested.