The total cross section for e+e− annihilation into hadrons has been measured for CM energies ranging from 50 to 57 GeV. We fit the predictions of the standard model to these measurements and those at lower energies. The mass of the Z0 boson, MZ, and the QCD scale parameter, ΛMS, are derived from the fit. The results are MZ=88.6−1.8+2.0 GeV/c2, and ΛMS=0.15−0.11+0.16 GeV.