  Although Planck data supports the standard \Lambda CDM model, it still allows
for the presence of Dark Radiation corresponding up to about half an extra
standard neutrino species. We propose a scenario for obtaining a fractional
"effective neutrino species" from a thermally produced particle which decays
into a much lighter stable relic plus standard fermions. At lifetimes much
longer than 1 sec, both the relic particles and the non-thermal neutrino
component contribute to Dark Radiation. By increasing the stable-to-unstable
particle mass ratio, the relic particle no longer acts as Dark Radiation but
instead becomes a candidate for Warm Dark Matter with mass O(1keV - 100GeV). In
both cases it is possible to address the lithium problem.
