In this report (a portion of a thesis presented by K. E. Irmen in partial fulfillment of the requirements for the M.S. degree in bacteriology at North Dakota State University), we describe a new temperate bacteriophage for a Bacillus pumilus lagoon isolate. In addition, the strain lysogenic for the new phage and the B. pumilus type strain (ATCC 7061) both harbor inducible particles which resemble "killer particles" reported for other Bacillus strains (1, 12). B. pumilus ATCC 7061 also produces a second type of phage-like particle upon induction.