This contribution aims to describe the development, cross validation and operationalization of a new scale developed to measure student self-perceived action competence. The underlying idea of education for sustainable development (ESD) is to empower young people to be sustainability action competent and thus, in the long run, contribute to transform the world into a more sustainable place (Lotz-Sitiska, Wals, Kronlid, & McGarry, 2015; Mogensen & Schnack, 2010, UNESCO, 2014). To be able to tune in and develop ESD processes and implementation strategies it is important to evaluate outcomes of ESD at the student level (Scott, 2013). Therefore, we set out to construct a reliable and valid instrument that covers action competence based on its definition in relation to sustainable development. The self-perceived action competence (SPAC) item battery was developed based on the definition of action competence by Danish researchers (Jensen & Schnack, 1997; Breiting & Mogensen, 1999). We built a higher order SEM model to validate the SPAC through confirmatory factor analysis. In our model, the student SPAC consists of three main parts (latent constructs): (KAP) knowledge of action possibilities, (COI) confidence in one’s own influence, and (WTA) a wish to act. The latent constructs KAP, COI and WTA are covered by four items respectively. 608 students aged 13-19 years old responded on a five-point Likert-scale (strongly disagree to strongly agree) to each of the twelve items. To cross validate the SPAC, the students also gave their answers to the short version (27 items) of the sustainability consciousness questionnaire (SCQs) (Gericke et al., 2018). The two scales were respectively validated with good model-fit. Moreover, the SPAC was translated into Dutch and cross validated with a group of Flemish students (n=403). The Flemish SPAC model was validated with good model fit. At the ECER conference in Hamburg, we will present the full 12-item scale and the full validation of the SPAC, including reliability measures of the scales and correlations between the Swedish and Flemish cohorts as well as the cross validation between the SPAC and SCQs for the Swedish data. We will invite the audience to share their thoughts on the relation between student self-perceived action competence and the action competence concept as an educational ideal. Feedback on strengths and shortcomings of our SPAC questionnaire will also be welcomed.