MINOS is a long baseline neutrino oscillation experiment. It measures the flux from the predominately muon neutrino NuMI beam first 1 km from beam start and then again 735 km later using a pair of steel scintillator tracking calorimeters. The comparison of measured neutrino energy spectra at our Far Detector with the prediction based on our Near Detector measurement allows for a measurement of the parameters which define neutrino oscillations. This thesis will describe the most recent measurement of muon neutrino disappearance in the NuMI muon neutrino beam using the MINOS experiment. The general method of a disappearance analysis at the MINOS experiment will be outlined, the selection of events, extrapolation between detectors, and fitting the data to the atmospheric mixing parameters. An analysis of the full MINOS Forward Horn Current charged current muon neutrino interactions sample is detailed, with a best fit to the atmospheric mixing parameters in a two flavour approximation of $\Delta |m^2_{atm}| = 2.42\times10^{-3}~\mathrm{eV}^2$ and $\sin^2(2\theta_{23}) = 0.936$. The change to a three flavor analysis with matter effects from a simple two flavour approximation is described, with a very slight preference of $-2\Delta \log(L)=0.01$ for the inverted hiearchy found. A study of the NuMI beam is also shown, with potential locations for new oscillation experiments in the NuMI beam discussed.