  Current status is described toward identifying unconventional order
parameters in filled skutterudites with unique ordering phenomena. The order
parameters in PrFe$_4$P$_{12}$ and PrRu$_4$P$_{12}$ are discussed in relation
to associated crystalline electric field (CEF) states and angular form factors.
By phenomenological Landau analysis, it is shown that a scalar order model
explains most properties in both PrFe$_4$P$_{12}$ and PrRu$_4$P$_{12}$ with
very different magnetic properties. In particular, the highly anisotropic
susceptibility induced by uniaxial pressure in PrFe$_4$P$_{12}$ is explained in
terms of two types of couplings. In the case of SmRu$_4$P$_{12}$, the main
order parameter at low field is identified as magnetic octupoles. A microscopic
mechanism is proposed how the dipole and octupole degrees of freedom mix under
the point group $T_h$ of skutterudites.
