  We discuss selected aspects regarding the magnetic field evolution of
solar-type stars. Most of the stars with activity cycles are in the range where
the normalized chromospheric Calcium emission increases linearly with the
inverse Rossby number. For Rossby numbers below about a quarter of the solar
value, the activity saturates and no cycles have been found. For Rossby numbers
above the solar value, again no activity cycles have been found, but now the
activity goes up again for a major fraction of the stars. Rapidly rotating
stars show nonaxisymmetric large-scale magnetic fields, but there is
disagreement between models and observations regarding the actual value of the
Rossby number where this happens. We also discuss the prospects of detecting
the sign of magnetic helicity using various linear polarization techniques both
at the stellar surface using the parity-odd contribution to linear polarization
and above the surface using Faraday rotation.
