An analysis of the language attitudes in the adjacent regions of Els Ports (in the province of Castellon, Spain) and Matarranya (in the province of Teruel, Spain) using the matched-guise technique shows that in both areas, Catalan and Spanish coexist today in a diglossic situation in which Catalan has instrumental values that are lower than those of Spanish. Nonetheless, analysis of some social factors (especially age) confirms that there are significant differences between the two language communities. We observed greater dynamism as regards this situation and more favourable attitudes to Catalan in Els Ports, especially among young people, and especially in terms of instrumental values. However, in Matarranya the diglossia is more stable and the attitudes towards Catalan are less positive. When analysing the causes of this significant difference, we considered the different general sociolinguistic situations in the two regions, which both belong to the Catalan language environment, and more specifically, the treatment the languages receive in their respective educational systems after several decades of linguistic normalisation policies in Spain. (Contains 1 figure, 4 tables, and 7 notes.)