  Using 85.2 +/- 3.6 pb^-1 of p-pbar collisions collected at sqrt(s)=1.8 TeV
with the D0 detector at Fermilab's Tevatron Collider, we present the results of
a search for direct pair production of scalar top quarks ~t, the supersymmetric
partners of the top quark. We examined events containing two or more jets and
missing transverse energy, the signature of light scalar top quark decays to
charm quarks and neutralinos. After selections, we observe 27 events while
expecting 31.1 +/- 6.4 events from known standard model processes. Comparing
these results to next-to-leading-order production cross sections, we exclude a
significant region of ~t and neutralino phase space. In particular, we exclude
the ~t mass m_~t < 122 GeV/c^2 for a neutralino mass of 45 GeV/c^2.
