  Notwithstanding it is well known that von Neumann's projection postulate is
inapplicable to most realistic measurement procedures, it keeps haunting the
foundations of quantum mechanics. In particular its applicability to EPR
experiments is often assumed. In the present contribution this problem is
considered from the point of view of a quantum mechanical theory of
measurement, allowing a treatment of projection in EPR experiments as a special
case of conditional preparation. The conditions are spelled out under which the
postulate may be applicable.
