  Variability studies are an important tool to investigate key properties of
stars and brown dwarfs. From photometric monitoring we are able to obtain
information about rotation and magnetic activity, which are expected to change
in the mass range below 0.3 solar masses, since these fully convective objects
cannot host a solar-type dynamo. On the other hand, spectroscopic variability
information can be used to obtain a detailed view on the accretion process in
very young objects. In this paper, we report about our observational efforts to
analyse the variability and rotational evolution of young brown dwarfs and very
low mass stars.
