A novel gypsum board having improved antimicrobial and antibacterial properties is disclosed. The board comprises a gypsum core, front and back paper facings, and a polymeric antimicrobial or antibacterial compound effective at inhibiting fungal growth. Preferred polymeric antimicrobial and antibacterial compounds include polyDADMAC, polyTMMC, and quaternized polyvinyl pyridine derivatives. The novel gypsum board further comprises a non-polymeric antimicrobial or antibacterial compound. Preferred non-polymeric antimicrobial or antibacteral compounds include cetyl pyridinium chloride and sodium pyrithione. The polymeric antimicrobial or antibacterial compound can be present in the gypsum core and/or on one or both of the paper facings. The non-polymeric antimicrobial or antibacterial compound may be encapsulated in a material or ionically associated with the polymeric antimicrobial or antibacterial compound to allow releases of the non-polymeric antimicrobial or antibacterial compound over time and/or upon exposure to moisture. Methods for preparing the aforementioned novel gypsum board are also disclosed.