  Co$_3$Sn$_2$S$_2$ has recently been predicted to be a Weyl semimetal in which
magnetic order is key to its behavior as a topological material. Here we report
unpolarized neutron diffraction and spherical neutron polarimetry measurements,
supported by magnetization and transport data, which probe the magnetic order
in Co$_3$Sn$_2$S$_2$ below $T_\textrm{C} = 177$ K. The results are fully
consistent with ferromagnetic order in which the spins on the Co atoms point
along the crystal $c$ axis, although we cannot rule out some canting of the
spins. We find no evidence for a type of long-ranged $(\textbf{k}=\textbf{0})$
in-plane 120$^\circ$ antiferromagnetic order which had previously been
considered as a secondary phase present at temperatures between $\sim$90 K and
$T_\textrm{C}$. A discontinuous change in bulk properties and neutron
polarization observed at $T = 125$ K when samples are cooled in a field and
measured on warming is found to be due to a sudden reduction in ferromagnetic
domain size. Our results lend support to the theoretical predictions that
Co$_3$Sn$_2$S$_2$ is a magnetic Weyl semimetal.
