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Nitrogen substituted zeolites with high crystallinity and microporosity are obtained by nitrogen substitution for oxygen in zeolite Y. The substitution reaction is performed under ammonia flow by varying the temperature and reaction time. We examine the effect of aluminum content and charge-compensating cation (H⁺/Na⁺/NH₄⁺) on the degree of nitrogen substitution and on the preference for substitution of Si−O−Al vs Si−O−Si linkages in the FAU zeolite structure. Silicon-29 magic angle spinning (MAS) nuclear magnetic resonance (NMR) and ¹H/²⁹Si cross-polarization MAS NMR spectroscopy have been used to probe the different local environments of the nitrogen-substituted zeolites. Experimental data are compared to simulated NMR spectra obtained by constructing a compendium (>100) of zeolite clusters with and without nitrogen, and by performing quantum calculations of chemical shifts for the NMR-active …