This theoretical program (analytical and numerical) by a collaboration of investigators from different institutions, is aimed at improving our understanding of the detectability of candidates for the "dark matter" that may make up 90% or more of the matter in the universe. It should help develop experiments for detecting "non-baryonic" dark matter and should make the search for dark matter candidates and other hypothetical but astrophysically relevant non-baryonic particles (e.g. axions, Majorons, familons) more effective. This project should increase the chances of detecting non- luminous, "dark" matter which may make up over 90% of the mass of the universe. Such detection would constitute a major, if not epochal, discovery whose full implications are hard to predict.