Magnetic properties of reduced titanium phosphate glasses are reported. Magnetic susceptibility measurements from 1.0° to 400°K indicates behavior typical for amorphous antiferromagnetism. The more reduced glasses show an anomalous field dependence in the susceptibility suggestive of ferromagnetism. A microstructural model for the glasses is developed from physical, chemical and magnetic data. Using the model, a theoretical magnetic susceptibility equation is derived. The equation includes contributions to a total susceptibility from isolated Ti(3+) ions and ion pairs which participate in exchange. From electron spin resonance results, the theoretical susceptibility equation and the experimental Ti(3+) ion concentration in the glasses, a good fit to the experimental magnetic susceptibility data is obtained. Results from the theoretical equation indicates that ferromagnetic and antiferromagnetic interaction between exchange‐coupled Ti(3+) ions may occur. At low temperatures a downward curve toward the origin of the inverse susceptibility is predicted which is consistent with the experimental data.