Local environments of molybdenum in glasses of the system (AgI)(y)-[(Ag2O)(x)-(MoO3)(1-x)](1-y) were investigated by use of near-infrared Fourier transform (NIR-FT) Raman spectroscopy, FT-IR spectroscopy, and Mo-95 magic-angle spinning (MAS) NMR. Specifically, the following cross-sections of the composition diagram were studied : series I : x = 0.5, and 0.50 less than or equal to y less than or equal to 0.75 and series II : y = 0.50, and 0.4 less than or equal to x less than or equal to 0.5. Comparison of the spectroscopic results with those obtained on crystalline model compounds indicates that the structures of series I-glasses (composition ratio Ag2O/MoO3 = 1) are solely based on Ag+, I-, and isolated MoO42-anions. On the other hand, glasses of series II (composition ratio Ag2O/MoO3 < 1) have a more complex structure consisting of both tetrahedral orthomolybdate, MoO42-, and a second, polynuclear species, in which MoO6 octahedra are linked to MoO4 tetrahedra in a manner similar to the structure of crystalline Na2Mo2O7.