A two-dimensional position-sensing detector for thermal neutrons was developed to improve the data collection in single-crystal neutron diffraction experiments, small-angle diffraction patterns from fibers and membranes, inelastic scattering measurements using the multiangle reflection crystal technique, nuclear and magnetic diffraction topography, and diffraction and transmission measurements on samples in which phase changes are occurring. The detector is a unique tool for rapid inspection of crystal quality, isolating grains, and alignment of a number of small crystals so that they reflect together for intensity enhancement. Simple diffraction experiments were made to illustrate the range of application. The camera consists of a neutron phosphor screen, image intensifier, television pick-up tube, and digital storage. The stored information can be displayed in one-and two-dimensional formats and transferred to magnetic tape for computer analysis. The camera resolution is 0.13 mm full width at half maximum (fwhm) horizontal and 1.0 mm vertical, which corresponds to more than 80000 detector elements over the useful area of the nominal 150 mm diameter phosphor screen. The counting rate per detector element is 60 regularly occurring events per second. The counting efficiency is ~15% for a 0-5 mm thick phosphor.