  A density functional theory study of the BiS$_{2}$ superconductors containing
rare-earths: \textit{Ln}O$_{1-x}$F$_{x}$BiS$_{2}$ (\textit{Ln} = La, Ce, Pr,
and Nd) is presented. We find that CeO$_{0.5}$F$_{0.5}$BiS$_{2}$ has competing
ferromagnetic and weak antiferromagnetic tendencies, the first one
corresponding to experimental results. We show that
PrO$_{0.5}$F$_{0.5}$BiS$_{2}$ has a strong tendency for magnetic order, which
can be ferromagnetic or antiferromagnetic depending on subtle differences in
4$f$ orbital occupations. We demonstrate that NdO$_{0.5}$F$_{0.5}$BiS$_{2}$ has
a stable magnetic ground state with weak tendency to order. Finally, we show
that the change of rare earth does not affect the Fermi surface, and predict
that CeOBiS$_{2}$ should display a pressure induced phase transition to a
metallic, if not superconducting, phase under pressure.
