Boron-doped ZnO films were prepared by pulsed laser deposition technique. Magnetic, electrical, and optical properties of Zn1-x B (x) O films have been studied. It is found that the magnetic properties of the Zn1-x B (x) O films are sensitive to growth oxygen partial pressure. The films deposited under a high oxygen partial pressure of about 10 Pa appear to be ferromagnetic insulators at room temperature (RT). However, when the oxygen partial pressure decreases to 1.2 Pa, the films are non-ferromagnetic conductors at RT. Zn vacancies, which can be controlled by the oxygen partial pressure, are shown to be essential for realizing ferromagnetism (FM); on the other hand, the n-type nature of ZnO has no contribution to the FM observed in the B-doped ZnO films.