Anaerobic lagoons are a major source of odor at concentrated animal feeding operations. Seven different kinds of artificial (geotextile & PE foam) and natural (straw & redwood) permeable lagoon covers were evaluated for their potential to reduce odorous emissions generated by anaerobic waste lagoons. A novel floating sampling raft was constructed and used to simultaneously evaluate the effectiveness of lagoon covers on an operating swine waste lagoon. The air collected from the raft was evaluated for odor strength (scentometer), hydrogen sulfide (Jerome meter), ammonia (electrochemical sensor), total hydrocarbons (flame ionization detector), and other odorous compounds. All lagoon covers substantially reduced hydrogen sulfide emissions and odor intensity. Geotextile fabric and a recycled foam cover exhibited the greatest reduction in total hydrocarbon emissions; natural covers were less effective. Due to consistently low emission rates of ammonia, no statistically significant reduction of ammonia emissions were observed from any of the lagoon covers.