Californium-252 makes an intense neutron point source that emits 2.34 × 1012 n/(sec g) through spontaneous fission. Sources are being prepared to investigate the value of this radionuclide for mineral, petroleum, and gas exploration, well logging and hydrology, activation analysis, neutron radiography, and other areas where isotopic neutron sources are used. Sources containing milligram amounts of 252Cf with active volumes of <25 mm3 are being prepared by precipitating and filtering californium oxalate on a small metallic filter, which is in the primary capsule in a totally enclosed apparatus. The oxalate is calcined to 252Cf2O3 before the primary capsule is sealed. These sources are doubly encapsulated under conservative design criteria to prevent leakage of radioactive material because they are used in a wide variety of environmental conditions. The neutron emission rate of the finished sources is within 10% of the desired value. Less than 1% of the 252Cf was lost in the process. Because the practical upper limit for the present capsule design is about ten milligrams of 252Cf, procedures are being developed for preparing sources containing up to several hundreds of milligrams of the isotope.