2,4-Dichlorophenol (2,4-DCP) was degraded anaerobically in freshwater lake sediments. From observed intermediates in incubated sediment samples and from enrichment cultures, the following sequence of transformations was postulated. 2,4-DCP is dechlorinated to 4-chlorophenol (4-CP), 4-CP is dechlorinated to phenol, phenol is carboxylated to benzoate, and benzoate is degraded via acetate to methane and carbon carbon dioxide. At least five different organisms are involved sequentially. The rate-limiting step was the transformation of 4-CP to phenol. Sediment-free enrichment cultures were obtained that catalyzed only the dechlorination of 2,4-DCP, the carboxylation of phenols, and the degradation of benzoate, respectively.