Much of the information regarding the nature of solid particles in interstellar space has been gained through the study of the line-of-sight extinction of starlight and the polarization of starlight by these particles. Study of the optical properties of these particles can be extended through consideration of the scattering of stellar radiation in reflection nebulae. This type of approach requires the adoption of models for the star-nebula system, and the grain type to be considered. These models are then used in a theory which describes the scattering of light by an ensemble of small particles, as applied to dust nebulae. Results are thus obtained for the colour of the nebula as a function of distance from the illuminating star. These results can then be compared with the corresponding results of experimental broad-band photometry.