It is well established that most low-index semiconductor surfaces reconstruct in contact with vacuum or vapor. Covalent bonding considerations imply that they also reconstruct in contact with the liquid. Conventional precipitation theory shows that these first-order transitions should have important consequences on the growth of the crystal. The kinetics of the Si (111) 2×1 to 7×7 reconstruction are explained and the consequent effect upon the growth is found in the observation by de Kock et al. of a 6-orders-of-magnitude drop in vacancy cluster concentration at a pull rate of 0.5 cm/min.