AbstractSoils from Times Beach, Missouri, containing from 8 ng g−1to 2.4 μg g−12,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) were examined for microbial activity. Parameters included enumeration of aerobic eutrophic and oligotrophic bacteria, fungi, and actinomycetes; enzymatic assays, including assays for dehydrogenase, arylsulfatase, rhodanese, and acid and alkaline phosphatases; and soil respiration (CO2evolution). The soils were also characterized for organic matter content, specific surface area, cation exchange capacity, pH, electrical conductivity, bulk density, particle size, and solvent‐extractable content. Compared with control soils, the TCDD‐contaminated soils showed considerable microbial activity and diversity, suggesting that TCDD is not microbially toxic at these concentrations and/or is no