  The weak production of Lambdas in nucleon-nucleon scattering is studied in a
meson-exchange framework. The weak transition operator for the $NN \to N
\Lambda$ reaction is identical to a previously developed weak
strangeness-changing transition potential $\Lambda N \to NN$ that describes the
nonmesonic decay of hypernuclei. The initial $NN$ and final $YN$ state
interaction has been included by using realistic baryon-baryon forces that
describe the available elastic scattering data. The total and differential
cross sections as well as the parity-violating asymmetry are studied for the
reaction $pn \to p\Lambda$. These observables are found to be sensitive to the
choice of the strong interaction potential and the structure of the weak
transition potential.
