Measurement of the Top Quark Mass

We present a measurement of the top quark mass using a sample of t-tbar decays into an electron or a muon, a neutrino, and four jets. The data were collected in p-pbar collisions at sqrt(s)=1.8 TeV with the Collider Detector at Fermilab and correspond to an integrated luminosity of 109 pb^-1. We measure the top quark mass to be 175.9 +/- 4.8(stat.) +/- 4.9(syst.) GeV/c^2.