In this review phosphorus-containing anions and molecules acting as ligands at calcium cations are discussed. Limitation to calcium derivatives is justified on the basis of its advantageous properties, its electropositive character ensuring high reactivity, and particularly the tremendous recent interest in calcium-based organometallics. Detailed discussions focus on substance classes such as phosphanides, phosphane oxides, phosphinites, phosphinates, and phosphonates. Isoelectronic relationships based on Grimm's hydride displacement law (such as O/NH/CH2 and also O/N−/CH−/C2−) allow categorization of calcium derivatives with phosphorus-containing anionic and neutral ligands. Applications of these compounds in stoichiometric and catalytic reactions are presented including very recent developments in calcium-mediated intermolecular hydrophosphanylation of alkynes.