Methods and compositions for producing flowable compositions, e.g. pastes, that set into calcium phosphate products are provided. In the subject methods, dry reactants that include a calcium source and a phosphate source are combined with setting fluid to produce the flowable composition. A feature of the subject methods is that the dry reactants include a particulate calcium and/or phosphate reactant having a mean particle size of less than about 8 .mu.m and narrow size distribution. Also provided are the compositions themselves as well as kits for use in practicing the subject methods. The subject methods and compositions produced thereby find use in a variety of applications, including the repair of hard tissue defects, e.g., bone defects.