  We revisit the no-scale mechanism in the context of the simplest no-scale
supergravity extension of the Standard Model. This model has the usual
five-dimensional parameter space plus an additional parameter $\xi_{3/2}\equiv
m_{3/2}/m_{1/2}$. We show how predictions of the model may be extracted over
the whole parameter space. A necessary condition for the potential to be stable
is ${\rm Str}{\cal M}^4>0$, which is satisfied if $\bf m_{3/2}\lsim2 m_{\tilde
q}$. Order of magnitude calculations reveal a no-lose theorem guaranteeing
interesting and potentially observable new phenomena in the neutral scalar
sector of the theory which would constitute a ``smoking gun'' of the no-scale
mechanism. This new phenomenology is model-independent and divides into three
scenarios, depending on the ratio of the weak scale to the vev at the minimum
of the no-scale direction. We also calculate the residual vacuum energy at the
unification scale ($C_0\, m^4_{3/2}$), and find that in typical models one must
require $C_0>10$. Such constraints should be important in the search for the
correct string no-scale supergravity model. We also show how specific classes
of string models fit within this framework.
