An automated vibrating‐sample magnetometer is described where the variable magnetic field in excess of ±1.1 T is produced in a 26 mm bore by an assembly of nested, rotating permanent magnet cylinders. The homogeneity is better than 0.3%±4 mT in 1 cc. The instrument has dimensions 200×420×700 mm, and its mass is 20 kg. Sensitivity is better than 0.4 &mgr;J/T (4×10−4emu), which permits study of the susceptibility, magnetization, and hysteresis of a wide range of magnetic materials, including ferromagnetic thin films.