  We explain how masses and matrix elements can be computed in lattice QCD
using Schr"odinger functional boundary conditions. Numerical results in the
quenched approximation demonstrate that good precision can be achieved. For a
statistical sample of the same size, our hadron masses have a precision similar
to what is achieved with standard methods, but for the computation of matrix
elements such as the pseudoscalar decay constant the Schr"odinger functional
technique turns out to be much more efficient than the known alternatives.
