  We have produced brightness and magnetic field maps of the surfaces of CV Cha
and CR Cha: two actively accreting G and K-type T Tauri stars in the Chamaeleon
I star-forming cloud with ages of 3-5 Myr. Our magnetic field maps show
evidence for strong, complex multi-polar fields similar to those obtained for
young rapidly rotating main sequence stars. Brightness maps indicate the
presence of dark polar caps and low latitude spots -- these brightness maps are
very similar to those obtained for other pre-main sequence and rapidly rotating
main sequence stars.
  Only two other classical T Tauri stars have been studied using similar
techniques so far: V2129 Oph and BP Tau. CV Cha and CR Cha show magnetic field
patterns that are significantly more complex than those recovered for BP Tau, a
fully convective T Tauri star.
  We discuss possible reasons for this difference and suggest that the
complexity of the stellar magnetic field is related to the convection zone;
with more complex fields being found in T Tauri stars with radiative cores
(V2129 Oph, CV Cha and CR Cha). However, it is clearly necessary to conduct
magnetic field studies of T Tauri star systems, exploring a wide range of
stellar parameters in order to establish how they affect magnetic field
generation, and thus how these magnetic fields are likely to affect the
evolution of T Tauri star systems as they approach the main sequence.
