The aim of this study was to develop and validate a scale to assess psychological well-being in physical activity and sport context, based on Ryff's theory (2014) and the definition of psychological well-being proposed Piñeiro et.al (2021). For that purpose, a Likert type instrument with 51 items was designed. The scale was applied to 584 participants (63% women) with aged between 15 and 29 years (M=19.05; SD 2.97), from secondary schools and universities from different autonomous communities of Spain. After the statistical analysis, eliminating the items with low values, the final instrument was composed with 40 items (6 dimensions). The results showed that the scale manifests high reliability (α= .965), as well as high levels of explained variance. In conclusion, the research provides a valuable instrument, supported by a scientific theoretical basis, for the evaluation of psychological well-being through physical activity and sports practice in Spanish youth.