The optical properties of neural tissues play critical roles in all types of optical imaging methods. The wavelength-dependent absorption and scattering properties of tissue influence imaging resolution, penetration depth, and often provide sources of contrast. Therefore, quantitative interpretation of imaging data requires knowledge of the optical properties of neural tissues. Light scattering in tissue arises from nanometer-scale spatial variations in refractive index and requires a thorough electromagnetic description of light propagation through this complex medium. Unfortunately, the complexity of neural tissues and the difficulty in measuring refractive index values make such a complete description unrealistic. Therefore, approximations must be made in order to characterize the light scattering properties of neural tissue. This chapter summarizes the various approaches to assess and describe the optical properties of neural tissue and discusses their role for cortical imaging.