  We present results of multifrequency polarimetric VLBA observations of 34
compact radio sources. The observations are part of a large survey undertaken
to identify CSOs Observed in the Northern Sky (COINS). Based on VLBI continuum
surveys of ~2000 compact radio sources, we have defined a sample of 52 CSOs and
CSO candidates. Positive identification of CSOs is contingent upon acquiring
multi-frequency observations in order to correctly identify the core of the
source, which is expected to have a strongly inverted spectrum. We also expect
CSOs to exhibit very little polarized flux. Despite the fact that synchrotron
emission is intrinsically highly polarized, less than 0.5% fractional
polarization is seen in low resolution studies of CSOs at frequencies up to 5
GHz. One possible explanation for the low observed linear polarization from
CSOs is that their radiation is depolarized as it passes through a magnetized
plasma associated with a circumnuclear torus. This interpretation is consistent
with the unified scheme of AGN, and also with the recent detections of
free-free and HI absorption in CSOs.
  Here we present limits on the polarized flux density at 8.4 GHz and ~1 mas
resolution for 21 CSOs and candidates in the COINS sample.
