  Scale invariance may be a classical symmetry which is broken radiatively.
This provides a simple way to stabilise the scale of electroweak symmetry
breaking against radiative corrections. But for such a theory to be fully
realistic, it must actually incorporate a hierarchy of scales, including the
Planck and the neutrino mass scales in addition to the electroweak scale. The
dark matter sector and the physics responsible for baryogenesis may or may not
require new scales, depending on the scenario. We develop a generic way of
using hidden sectors to construct a technically-natural hierarchy of scales in
the framework of classically scale-invariant theories. We then apply the method
to generate the Planck mass and to solve the neutrino mass and dark matter
problems through what may be termed the "scale-invariant standard model". The
model is perturbatively renormalisable for energy scales up to the Planck mass.
