Contradictory evidence has led to contrasting hypotheses as regards the origin in Actinia equina. L. of the juvenile anemones which may be found being brooded within adults. We have found, in a North Yorkshire population, a very low proportion of males, but these, as well as individuals lacking gonads, often contained young. All young resembled in colour the adults from which they were obtained. Adults maintained in isolation so as to prevent fertilization continued to produce young. Also ova apparently undergoing cell division were found within female gonads. By contrast, small fragments of anemone, although adopting the appearance of larvae, when cultured, do not develop into juveniles. We conclude that within the population studied reproduction is most probably by parthenogenesis.