Calcium phosphate nanoclusters are equilibrium particles of defined chemi-cal composition in which a core of amorphous calcium phosphate is sequestered within a shell of casein phosphopeptides. Sequence analyses and a structure prediction method were applied to secreted phosphopro-teins of known importance in controlling calcification, and eight noncasein phosphoproteins were identified as containing one or more subsequences capable of forming nanoclusters.