Apparatus suitable for variable wavelength and incident angle second harmonic ellipsometry (SHE) studies of solid and liquid interfaces is introduced, with particular attention drawn to the calibration of the experiment. Preliminary results obtained from the study of the chiral molecule 1, 1'-bi-2-naphthol located at the air/water interface are used to indicate the suitability of SHE as a surface probe for resonant systems including the determination of the interfacial refractive index at the harmonic frequency.