  We study the dynamics of a quantum particle in R^(n+m) constrained by a
strong potential force to stay within a distance of order hbar (in suitable
units) from a smooth n-dimensional submanifold M. We prove that in the
semiclassical limit the evolution of the wave function is approximated in norm,
up to terms of order hbar^(1/2), by the evolution of a semiclassical wave
packet centred on the trajectory of the corresponding classical constrained
system.
