  The MACHO collaboration reports on the analysis of our first year LMC data,
9.5 million light curves with an average of 235 observations each. Automated
selection procedures give 3 events consistent with microlensing. We evaluate
our experimental detection efficiency using a range of Monte- Carlo
simulations. Using a `standard' halo density profile we find that a halo
comprised entirely of Machos in the mass range 3 \ten{-4} to 0.06 \msun would
predict > 15 detected events in this dataset; thus a standard spherical halo
cannot be dominated by objects in this mass range. Assuming all three events
are microlensing of halo objects and fitting a naive spherical halo model to
our data yields a Macho halo fraction f =0.19+0.16-0.10, a total mass in Machos
(inside 50 kpc) of 7.6+6-4 \ten{10} \msun, and a microlensing optical depth
8.8+7-5 \ten{-8} (68\% CL). Exploring a wide range of halo models we find that
our constraints on the Macho fraction are quite model-dependent, but
constraints on the total mass in Machos within 50 kpc are quite secure.
