High-level density functional electronic structure calculations have been performed to analyze the effect of microsolvation with water on the electronic properties of ortho-aminobenzoic acid (o-Abz). The hydrogen-bonded interaction of the o-Abz molecule with one to three water molecules, o-Abz···(H2O)n (n = 1–3), has been considered in two different situations, once the solvent water molecules are placed close to the carboxyl (−COOH) group of o-Abz producing the o-Abz···[H2O]nCOOH complexes and when the water molecules are placed close to the amino (−NH2) group producing the o-Abz···[H2O]nNH2 clusters. Variation of the vibrational spectra and energetics upon hydrogen-bond formation are analyzed and compared with available experimental data. The effect of cooperativity is also analyzed. Overall, the hydrogen-bonded o-Abz···[H2O]nCOOH clusters are found to be more stable than the o-Abz···[H2O]nNH2 clusters.