  The lifetime of the Bs0 meson is measured using the semileptonic decay Bs0
--> Ds- l+ nu X. The data sample consists of about 110 pb^-1 of pp= collisions
at sqrt{s} = 1.8 TeV collected by the CDF detector at Fermilab. Four different
Ds- decay modes are reconstructed resulting in approximately 600 Ds-l+ signal
events. The Bs0 meson lifetime is determined to be tau(Bs0) = (1.36 +- 0.09
+0.06-0.05) ps, where the first and second uncertainties are statistical and
systematic, respectively. The Bs0 meson decay length distribution is examined
for a lifetime difference Delta_Gamma/Gamma between the two mass eigenstates of
the Bs0 meson. An upper limit of Delta_Gamma/Gamma < 0.83 is set at 95%
confidence level.
