Methyl-p-aminobenzoate(NH3)(1), complex, henceforth MAB(NH3)(1), prepared in a pulsed supersonic expansion, has been examined by laser mass-selective spectroscopies and density functional theory calculations, aiming to ascertain its isomer number, structures, identification, ionization energies, and vibrational assignments. Resonance enhanced multiphoton ionization and hole burning spectra of the species in supersonic beams show two 0(0)(0) transitions redshifted by -715 and -709 cm(-1) from that of bare MAB band origin and are plausibly associated with two different isomers, whereas ab initio calculations indicate the likely existence of five stable isomer structures. Identification of the experimental isomer spectra with the calculated structures is reported and, in particular, several isomer vibrational bands are identified by contrast with the calculated modes. Properties and features of the MAB(NH3)(1) are compared with those of the MAB/water complexes.