<pre>In Reuven Feuerstein's Cognitive Structural Modifiability Theory, 12 dimensions characterize teacher mediation, four of them are universal: <em>intentionality and reciprocity</em>; <em>transcendence</em>; <em>meaning</em>; <em>awareness of modifiability</em>. To validate the instrument aimed at evaluating the quality of teaching mediation, a sample of 531 undergraduates from 12 undergraduate courses, whose average age was 22.5 years (standard deviation 3.6 years), with a gender predominance (n = 309 or 58.2%) and the majority came from baccalaureate (n = 359 or 67.6%). The results showed a factorial structure in which the 26 assertions of the instrument were grouped into the four universal factors, with very high indexes of validity (self-values between 1.33 and 9.14, explained variance between 5.13% and 35.15 %) and reliability (Cronbach's alphas between 0.71 and 0.91). The analysis of Variance (ANOVA) detected significant differences in the quality of teacher mediation of the courses in the areas of Human Sciences, Health Sciences and Technology in three of the universal factors (F = 12.96; p &lt; 0.001 - Factor intentionality and reciprocity; F = 5.42, p &lt; 0.001 - Factor transcendence, F = 13.40, p &lt; 0.001 - Factor awareness of the modifiability). It is concluded that the instrument has a high degree of confidence and validity, and can be used to evaluate the quality of teacher mediation in a university environment.</pre>