Remote sensing of major and minor constituents in the earth's atmosphere is of great importance to the study of climate and global change. Because much of remote sensing involves placing instrumentation in environments that are not easily accessible, such as balloons, spacecraft, or remote field stations, it is usually necessary that the instrumentation be compact, lightweight, and rugged. This paper describes the development of a new type of remote sensing instrument we have chosen to call the multiplex Fabry-Perot interferometer (MFPI). We present atmospheric spectra obtained with our working prototype instrument. The MFPI is a Fabry-Perot interferometer for which the etalon plate separation is changed over a large optical distance during a measurement. When the resulting interferogram is Fourier transformed the multiple reflections within the etalon cavity produce a spectrum analogous to that which would be produced by an array of Michelson interferometers. However, for high spectral resolution measurements the scan distance required by the MFPI is much less than for the comparable Michelson. The MFPI will be ideal for remote sensing applications where weight, size, and mechanical reliability are primary considerations.