Composite plaster panels, compositions used to make composite plaster panels, and methods for manufacturing composite plaster panels. Composite plaster panels include a core composite panel structure and a plaster layer applied to and at least partially covering at least one side of the core composite panel structure. The core composite panel structure includes a foam core sandwiched between thin protective layers (e.g., fiber mesh reinforced cementitious layer or thermoset polymer layer). The plaster layer includes reaction products of water, Portland cement, preferably, white cement, calcium carbonate, aluminum oxide, silicon dioxide, cellulose ether, and latex. The composite plaster panels can be used to replace gypsum drywall panels and are advantageously lighter weight, have beveled edges, and can have a smooth or textured plastic layer. The composite plaster panels can be cut, drilled, and screwed onto structural elements of buildings, such as wall frames comprising wooden or metal studs or ceiling joists.