The wavelength dependence of the integrated and peak reflectivities of distorted copper single crystals has been measured and the results compared with calculated values obtained from Bacon and Lowde's model of an ideally imperfect mosaic crystal. The effects of simultaneous reflections on the reflected neutron intensities were studied and accounted for in terms of an effective absorption coefficient. A non-Gaussian mosaic block distribution function was successfully introduced to bring about better agreement between experimental and calculated curve shapes. Using this technique, the desired agreement in curve shape was attained but, in order to bring measured and calculated absolute reflectivities into better agreement, it was necessary to include primary extinction effects. / Thesis / Master of Science (MSc)