Background: Enhancing students' critical thinking (CT) is an essential goal of higher education. Although there are many instruments to assess its cognitive dimension, this is not so in the case of dispositional thinking. Our aim is to examine the psychometric properties of the Spanish version of the Critical Thinking Disposition Scale (CTDS; Sosu, 2013). Method: Data come from 1064 students in their final years at high school and university in Spain. We report validity evidence based on its internal structure by confirmatory factor analysis (CFA) and an estimation of reliability and measurement invariance by gender. Additionally, nomological validity study with a multiple-indicator multiple-causes, MIMIC model, for the university students is provided. Results: Three CFAs are reported, with evidence supporting the one-factor structure as the best representation of the data: χ2(44) = 413.556 (p < .001); CFI = .976; RMSEA = .089[.081,.097]; SRMR = .031; ECV = .889. With this structure, measurement invariance between boys and girls is tested and the scalar model is retained. Differences in latent means are found, favoring girls (d = 0.449; se = .065; p < .001). The reliability of CTDS is adequate, with a Cronbach's alpha of .777 and a CRI value of .925. When tested in university students, the MIMIC model offers evidence for nomological validity: higher levels are found for women (β =.111, p < .050) and also for those with higher levels of rational thinking (β = .577, p < .010). Conclusions: The Spanish version of the CTDS has good psychometric properties (including gender measurement invariance not yet reported in literature), and is suitable for being used to measure the disposition to critical thinking in youth. The relevance and implications of these results are further discussed.