This paper describes a novel packaging design for a lithium niobate Mach-Zehnder interferometric modulator. The modulator is mounted to the bottom of a miniature carrier using elastic supports to minimize transmission of bending, random vibration and shock loads. Optical fibers are threaded from the modulator ends to the outside world via tubular feed- throughs located to allow for thermal expansion of the carrier without inducing stress on the fibers. An electric current board is attached to the carrier, and wire bonds from the board to the modulator provide the required voltages. The total package envelope is less than 0.41 in3 in volume. A major design goal was to achieve a hermetically sealed package, using all-metallic seals wherever possible. The package cover is resistance-seam-welded over the carrier top. However, as an intermediate step in the development process, the optical fibers are sealed with epoxy at the feed-through locations, rather than with solder seals to metallized fibers, which would provide a true hermetic seal. The paper provides supporting analysis performed to demonstrate the effectiveness of the design, including the epoxy seals, as well as experimental test results which validate the design.