  The study of the longitudinal polarization of Lambda and Lambda-bar hyperons
produced in polarized deep inelastic scattering, neutrino scattering, and in Z0
decays allows to access the spin dynamics of the quark fragmentation process.
Different phenomenological spin transfer mechanisms are considered and
predictions for the Lambda and Lambda-bar longitudinal polarization in various
processes using unpolarized and polarized targets are made. Current and future
semi-inclusive deep inelastic scattering experiments will provide soon accurate
enough data to study these phenomena and distinguish between various models for
the spin transfer mechanisms.
