A process is disclosed of preparing a photographic emulsion containing tabular silver halide grains exhibiting a reduced degree of total grain dispersity. After forming a population of silver halide grain nuclei containing parallel twin planes, ripening out a portion of the silver halide grain nuclei. The silver halide grain nuclei containing parallel twin planes remaining are then grown to form tabular silver halide grains. The total grain dispersity of the emulsion is reduced by incorporating bromide ion in the dispersing medium prior to forming the silver halide grain nuclei and, at the time parallel twin planes are formed in the silver halide grain nuclei, a polyalkylene oxide block copolymer surfactant containing terminal hydrophilic alkylene oxide block units linked by a lipophilic alkylene oxide block unit accounting for at least 4 percent of the molecular weight of the copolymer.