The present study features 1H and 27Al MAS NMR spectroscopic investigations on mixed ligand metal-organic frameworks (MOFs) of MIL-53(Al) type with benzene-1,4-dicarboxylate (BDC) and 2-aminobenzene-1,4- dicarboxylate (ABDC) linkers. The excellent resolution of the 1H spectra allowed an elegant and facile quantitative analysis of the organic linkers using solid-state NMR. The actual molar fraction of ABDC in the dehydrated mixed linker MOFs was determined by evaluating the intensity of the -NH2 signal at 5.6 ppm. The incorporation of amine groups led to higher field shifts of the corner-sharing AlOH signals and a more homogeneous charge distribution in the local structure of framework aluminum atoms corresponding to a decrease of the quadrupole coupling constant by ∼1 MHz compared to that of aluminum coordinated to BDC. Upon rehydration, the local structures of the framework aluminum atoms exhibited a much lower symmetry, as indicated by an increase of the 27Al quadrupole coupling constant by up to 3 MHz.