We propose that far-infrared reflection and transmission measurements would be a sensitive probe of possible variations in the polarizationPof a ferroelectric near a surface. We present a general formulation based on the Landau-Devonshire model, including both linear and nonlinear processes. Surface effects are described by parametersD, giving the free-energy cost of spatial variations inP, and δ, governing the boundary condition onP. Detailed calculations for linear reflection in normal incidence from a semi-infinite medium are presented. If δ−1= 0 the calculations are analytic and the results for this case serve as a check on the numerical calculations that are applied for general δ. Altogether, the results suggest that the effects ofDand δ should be distinct and measurable.