Deuterated Ammonia in Galactic Protostellar Cores

We report on a survey of h2d towards protostellar cores in low-mass star formation and quiescent regions in the Galaxy. Twenty-three out of thirty-two observed sources have significant ($gsim 5sigma$) h2d emission. Ion-molecule chemistry, which preferentially enhances deuterium in molecules above its cosmological value of scnot{1.6}{-5} sufficiently explains these abundances. NH2D/NH3 ratios towards Class 0 sources yields information about the ``fossil remnants from the era prior to the onset of core collapse and star formation. We compare our observations with predictions of gas-phase chemical networks.