  We study twist expansions for parton fragmentation functions based on the
definition of the twist as an invariant matrix element of a light-cone, bilocal
operator. The results are then applied to a method which might be used to
extract higher twist effects in the fragmentation sector using both $e^+ e^-$,
and $e^- p$ collisions. We discuss how to apply the later measurements to
experiments at the Jefferson National Acceleration Facility.
