The magnetization of thin films of cobalt ferrite frequently falls far below the bulk value of 455 kAm -1 , which corresponds to an inverse cation distribution in the spinel structure with a significant orbital moment of about 0.6 µB that is associated with the octahedrally-coordinated Co 2+ ions. The orbital moment is responsible for the magnetostriction and magnetocrystalline anisotropy, and its sensitivity to imposed strain. We have systematically investigated the structure and magnetism of films produced by pulsed-laser deposition on different substrates (TiO2, MgO, MgAl2O4, SrTiO3, LSAT, LaAlO3) and as a function of temperature (500-700C) and oxygen pressure (10 -4 -10 Pa). Magnetization at room-temperature ranges from 60 to 440 kAm -1 , and uniaxial substrate-induced anisotropy ranges from +220 kJm -3 for films on deposited on MgO (100) to -2100 kJm -3 for films deposited on MgAl2O4 (100), where the roomtemperature anisotropy field reaches 14 T. No rearrangement of high-spin Fe 3+ and Co 2+ cations on tetrahedral and octahedral sites can reduce the magnetization below the bulk value, but a switch from Fe 3+ and Co 2+ to Fe 2+ and low-spin Co 3+ on octahedral sites will reduce the lowtemperature magnetization to 120 kAm -1 , and a consequent reduction of Curie temperature can bring the room-temperature value to near zero. Possible reasons for the appearance of low-spin cobalt in the thin films are discussed.