  Recent observational and theoretical results emphasize the potential
significance of magnetic fields for structure, evolution, and environment of
massive stars. Depending on their spectral and photometric behavior, the upper
main-sequence B-type stars are assigned to different groups, such as beta Cep
stars and slowly pulsating B (SPB) stars, He-rich and He-deficient Bp stars, Be
stars, BpSi stars, HgMn stars, or normal B-type stars. All these groups are
characterized by different magnetic field geometry and strength, from fields
below the detection limit of a few Gauss up to tens of kG. Our collaboration
was the first to systematically study the magnetic fields in representative
samples of different types of main-sequence B stars. In this article, we give
an overview about what we have learned during the last years about magnetic
fields in beta Cep, SPB, and Be stars.
