This invention relates to a synergistic combination of molybdate salts (e.g., calcium molybdate) and magnesium hydroxide to suppress both smoke and flame in polymeric compositions, such as plastic piping, profile applications, wire and cable, semiconductor and electrical conduit application, to name a few. In some embodiments, the technology relates to polyvinyl chloride (“PVC”) and chlorinated polyvinyl chloride (“CPVC”) compounds, among other polymer resin containing compounds, having improved smoke and flame performance from the synergistic combination of molybdate salts and magnesium hydroxide.