Abstract We report on the extension of resonant magnetic diffraction into the soft X-ray region (500–1500 eV). We conducted soft X-ray diffraction from a bulk single crystal of La 2−2 x Sr 1+2 x Mn 2 O 7 using an in-vacuum diffractometer. We demonstrate that the resonant enhancement diffraction of the (0 0 1) magnetic peak at the manganese L III and L II absorption edges is extremely large. Measurements taken on samples with different strontium dopings demonstrate that the shape of the energy resonance is also dependent on the sample stoichiometry. We have applied this technique to the study of other materials such as UAs 1− x Se x where incommensurate magnetic diffraction has been observed at the uranium N IV and N V edges.