  The most important hint of physics beyond the Standard Model (SM) from the
1995 precision electroweak data is that the most precisely measured quantities,
the total, leptonic and hadronic decay widths of the $Z$ and the effective weak
mixing angle, $\sin^2\theta_W$, measured at LEP and SLC, and the quark-lepton
universality of the weak charged currents measured at low energies, all agree
with the predictions of the SM at a few $\times 10^{-3}$ level. By taking into
account the above constraints I examine implications of three possible
disagreements between experiments and the SM predictions. It is difficult to
interpret the 11\% (2.5-$\sigma$) deficit of the $Z$-partial-width ratio
$R_c=\Gamma_c/\Gamma_h$, since it either implies an unacceptably large
$\alpha_s$ or a subtle cancellation among hadronic $Z$ decay widths in order to
keep all the other successful predictions of the SM. The 2\% (3-$\sigma$)
excess of the ratio $R_b=\Gamma_b/\Gamma_h$ may indicate the presence of a new
rather strong interaction, such as the top-quark Yukawa coupling in the
supersymmetric (SUSY) SM or a new interaction responsible for the large
top-quark mass in the Technicolor scenario of dynamical electroweak symmetry
breaking. Another interpretation may be additional tree-level gauge
interactions that couple only to the third generation of fermions. A common
consequence of these attempts is a rather small $\alpha_s$, $\alpha_s(\mz
)_{\msbar}=0.104\pm 0.08$. The 0.17\% (1-$\sigma$) deficit ...
