We present a measurement of the W boson mass using data collected by t
he D0 experiment at the Fermilab Tevatron during 1994-1995. We identif
y W bosons by their decays to e nu final states. We extract the W mass
M-W by fitting the transverse mass and transverse electron momentum s
pectra from a sample of 28 323 W -->e nu decay candidates. We use a sa
mple of 3563 dielectron events. mostly due to Z --> ee decays, to cons
train our model of the detector response. From the transverse mass fit
we measure M-W = 80.44 +/- 0.10 (stat) +/- 0.07 (syst) GeV. Combining
this with our previously published result from data taken in 1992-199
3, we obtain M-W = 80.43 +/- 0.11 GeV. [S0556-2821(98)03519-X].