Three different individuals of Octopus vulgaris laid eggs in the Society's Aquarium in September 1957, May 1960 and August 1960 respectively. Mating was observed in the first instance. The eggs were brooded for a period of thirty-nine to forty-two days. The larvae hatched successfully, but did not feed, although offered a variety of foods, and survived for an average of eight days. In each case the mother died immediately or shortly after the hatching of the last larvae. The behaviour of the female during brooding is described.