SUMMARY Bacteriophage-like particles were induced from 6 of 21 strains of stalked bacteria, using mitomycin C or ultraviolet irradiation as the inducing agents. The phage inductions were observed in strains of Caulobacter crescentus, C. vibrioides and C. bacteroides. The phage-like particles were observed, using electron microscopy. Two of the phage-like entities, tentatively designated defective phages, could not be propagated on any of 2I potential host strains tested, nor did they possess bacteriocin activity. Host strains which permitted lyric cycles of phage replication were found for four induced phages .These bacteriophages contained double-stranded DNA. The bacterial strains from which they were induced were iresistant to infection by their respective phage. Four bacterial strains were treated with specific antiphage serum, but clones so treated retained their capacity to produce the phages. The inefficacy of antiphage serum in curing the bacteria of phage suggested that these Caulobacter strains were lysogenic.