Multiphoton microscopy is an important tool for high-resolution imaging of turbid media. A fundamental limit of the technique is the excitation produced outside of the focal region. The ratio of the signal at the focus to the background--the signal-to-background ratio, or SBR--is one important quantity that determines the limit of depth that can be imaged in a multiphoton experiment. While it is often believed that only unscattered light contributes to this background, scattered light is also a significant component. In this thesis a convolutional method of solving for scattered light will be used and adjusted for the multiphoton problem. Additionally, a novel Monte Carlo formulation is implemented on the GPU for this same purpose. The two techniques give similar results for produced excitations and SBR. Both demonstrate the primary importance of scattered light in the generation of out-of-focus excitation. Each method also shows the strong dependence of the SBR on a variety of illumination and optical properties.