The design possibilities and limitations of multilayer structures for soft x‐ray spetroscopy are summarized. Near grazing incidence structures can have a large integrated reflectivity and a large relative bandwidth close to one. The smallest possible bandwidth or highest possible resolution is obtained ner normal incidence, and is determined by the absorption index k of the most transparent material available; the maximum resolution in Nmax≂1/2πk. Depending on the wavelength, values for Nmax can be between 10 and 104 in the soft x‐ray region. The practical realization of a design requires good thickness control and sharp, smooth boundaries between the layers. Sufficient thickness control has been obtained by in situ monitoring of the x‐ray reflectivities. Within the uncertainties of the optical constant the measured performance of the best multilayer systems is in agreement with theory for multilayer periods larger than 30Å. For smaller period lengths, the peak reflectivity is smaller than the theoretical values. The lower reflectivity can be explained by an effective roughness of the multilayer system in the order of 3Å.