We have studied impurity redistribution due to low-temperature crystallization of amorphous silicon. Many impurities move ahead of the amorphous-crystalline interface and relocate closer to the surface. In general, redistribution is more likely at high impurity concentrations. By investigating a wide range of concentrations for indium, lead, and antimony, we demonstrate the direct correlation between the magnitude of this redistribution effect and the impurity metastable solubility limit in crystalline silicon. At low concentrations, it is less likely for impurities to redistribute. However, in this regime we show that indium experiences concentration-independent segregation, and that boron profiles are also affected by the crystallization process.