The present invention relates to stable and biodegradable foamed cement slurries, additives and methods. A foamed cement slurry of the invention comprises a hydraulic cement, sufficient water to form a slurry, sufficient gas to form a foam and a biodegradable foaming and stabilizing additive comprising a mixture of a capryl/capramido propyl betaine surfactant and a capryl/capramido propyl dimethyl amine oxide surfactant.