  A supersymmetric model with four generations is proposed, in which the top
quark is approximately degenerate in mass with the $W^{\pm}$ gauge boson,
$m_t\simeq m_W$, leading to values of $R_b$ in better agreement with the
present experimental data than in the Standard Model. The model shares many of
the good features of the minimal supersymmetric extension of the Standard Model
(MSSM), such as the unification of gauge and Yukawa couplings at a common
high-energy scale. The model differs from the MSSM by re-interpreting the
Tevatron ``top-quark'' events as the production of the fourth generation quark
$t\pri$, which decays dominantly to $bW^+$. The top quark decays primarily into
supersymmetric particles, $t\rta\widetilde t\widetilde\chi^0_1$, with
$\widetilde t\rta c\widetilde\chi^0_1$, thereby evading previous searches.
Light supersymmetric particles are predicted to lie in the mass range between
25 and 70 GeV, which together with the fourth generation leptons provide a rich
spectrum of new physics which can be probed at LEP-2 and the Tevatron.
