  We present a preliminary direct measurement of the parity violating coupling
of the Z boson to strange quarks, A_s, derived from a sample of approximately
300,000 hadronic decays of Z bosons produced with a polarized electron beam and
recorded by the SLD experiment at SLAC between 1993 and 1997. Events with
primary strange quarks are tagged by the presence in each event hemisphere of a
high-momentum charged K meson, neutral K meson or Lambda hyperon identified
using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex
detector is used to suppress the background from heavy flavor events. The
strangeness of the tagged particle is used to sign the event thrust axis in the
direction of the initial strange quark. The coupling A_s is obtained directly
from a measurement of the left-right-forward-backward production asymmetry in
polar angle of the tagged strange quark. To reduce the model dependence of the
measurement, the background from primary up and down events is measured from
the data, as is the analyzing power of the method for primary strange events.
We measure A_s = 0.82+-0.10(stat.)+-0.08(syst.) (preliminary).
