  We formulate an $SU(8)$ family unification model motivated by requiring that
the theory should incorporate the graviton, gravitinos, and the fermions and
gauge fields of the standard model, with boson--fermion balance. Gauge field
$SU(8)$ anomalies cancel between the gravitinos and spin $\frac {1}{2}$
fermions. The 56 of scalars breaks $SU(8)$ to $SU(3)_{family} \times
SU(5)\times U(1)/Z_5$, with the fermion representation content needed for
"flipped" $SU(5)$ with three families, and with residual scalars in the $10$
and $\overline{10}$ representations that break flipped $SU(5)$ to the standard
model. Dynamical symmetry breaking can account for the generation of $5$
representation scalars needed to break the electroweak group. Yukawa couplings
of the 56 scalars to the fermions are forbidden by chiral and gauge symmetries,
so in the first stage of $SU(8)$ breaking fermions remain massless. In the
limit of vanishing gauge coupling, there are $N=1$ and $N=8$ supersymmetries
relating the scalars to the fermions, which restrict the form of scalar
self-couplings and should improve the convergence of perturbation theory, if
not making the theory finite and "calculable". In an Appendix we give an
analysis of symmetry breaking by a Higgs component, such as the $(1,1)(-15)$ of
the $SU(8)$ 56 under $SU(8) \supset SU(3) \times SU(5) \times U(1)$, which has
nonzero $U(1)$ generator.
