The principles of double modulation FT-IR circular dichroism are presented. This approach to the measurement of infrared circular dichroism is compared to other methods and the advantages of the double modulation technique are explained. Examples of FT-IR vibrational circular dichroism (VCD) are presented and compared to the same VCD spectra measured with a conventional dispersive instrument. Procedures for calibrating the FT-IR-VCD spectra are noted and the performance of the instrument is evaluated for signal-to-noise ratio and interfering polarization artifacts.