  We present Halpha spectropolarimetry of a large sample of pre-main sequence
(PMS) stars of low and intermediate mass, and argue that the technique is a
powerful tool in studying the circumstellar geometry around these objects. For
the intermediate mass (2 -- 15 Msun) Herbig Ae/Be stars we find that 16 out of
23 show a line effect, which immediately implies that flattening is common
among these objects. Furthermore, we find a significant difference in Halpha
spectropolarimetry behaviour between the Herbig Be and Ae groups. For the
Herbig Be stars, the concept of an electron scattering disc is shown to be a
useful concept to explain the depolarizations seen in this spectral range. At
lower masses, more complex Halpha polarimetry behaviour starts to appear. The
concept of a compact source of Halpha emission that is formed close to the
stellar surface, for instance by hot spots due to magnetospheric accretion, is
postulated as a working hypothesis to qualitatively explain the Halpha
spectropolarimetry behaviour around Herbig Ae and lower mass (M < 2 Msun) T
Tauri stars. The striking resemblance in spectropolarimetric behaviour between
the T Tauri star RY Tau and the Herbig Ae stars suggests a common origin of the
polarized line photons, and hints that low and higher mass pre-main sequence
stars may have more in common than had hitherto been suspected.
