  We show that for any effective field theory of colorless meson fields, the
mixing schemes of particle states and decay constants are not only related but
also determined exclusively by the kinetic and mass Lagrangian densities. In
the general case, these are bilinear in terms of the intrinsic fields and
involve non-diagonal kinetic and mass matrices. By applying three consecutive
steps this Lagrangian can be reduced into the standard quadratic form in terms
of the physical fields. These steps are : (i) the diagonalization of the
kinetic matrix, (ii) rescaling of the fields, and (iii) the diagonalization of
the mass matrix. In case, where the dimensions of the non-diagonal kinetic and
mass sub-matrices are respectively, $k\times k$ and $n\times n$, this procedure
leads to mixing schemes which involve $[k(k-1)/2] + [n(n-1)/2]$ angles and $k$
field rescaling parameters. This observation holds true irrespective with the
type of particle interactions presumed. The commonly used mixing schemes,
correspond to a proper choice of the kinetic and mass matrices, and are derived
as special cases. In particular, $\eta$-$\eta '$ mixing, requires one angle, if
and only if, the kinetic term with the intrinsic fields has a quadratic form.
