A gypsum cellulose fiber composite board having a cellulosic fiber layer on at least one surface layer of the composite material is disclosed. A continuous method for preparing the composite board is described wherein a cellulosic fiber first slurry is deposited on a traveling web from a head box to form a first cellulosic layer and a co-calcined gypsum and cellulosic fiber second slurry is deposited to form a co-calcined gypsum and cellulosic fiber second layer on the cellulosic first layer. If desired a cellulosic fiber third layer is deposited or coated on top of the co-calcined gypsum and cellulosic fiber second layer. A method including laminating a layer of wallboard paper to at least one surface of a co-calcined gypsum and cellulosic fiber composite panel is also disclosed.