MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. By measuring the neutrino interactions in a detector near the neutrino source and again 735 km away from the production site, it is possible to probe the parameters governing neutrino oscillation. The majority of the ν µ oscillate to ν τ but a small fraction may oscillate instead to ν e . This thesis presents a measurement of the ν e appearance rate in the MINOS far detector using the first two years of exposure. Methods for constraining the far detector backgrounds using the near detector measurements is discussed and a technique for estimating the uncertainty on the background and signal selection are developed. A 1.6σ excess over the expected background rate is found providing a hint of ν e appearance.iii

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