  Strong commensurate antiferromagnetism proximate to superconductivity is
found in some members of the kappa-(ET) family, while a spin gap (SG) is found
in the theta-(ET). Both kappa- and theta-(ET) materials have frustrated
triangular lattice structures. We show from calculations of spin-spin
correlations within the effective half-filled band triangular lattice proposed
for the kappa-ET, as well as for the real lattice, that long range AFM order is
not obtained as a consequence of this frustration. We argue that some other
mechanism reduces the magnetic frustration in these systems. We show that the
low temperature magnetic states in these materials can only be understood if
the effects of the {\it cooperative} charge and bond ordering transitions
occurring at higher temperatures in these systems are taken into account. In
the kappa-ET, this co-operative transition leads to unequal hole populations on
the ET dimers that form the triangular lattice.
