This Communication demonstrates how selectively functionalized, patterned microscale wells can be used as small-volume (fL) crystallization vessels to grow protein crystals. This surface-patterned approach enables proteins to be crystallized with well-controlled shapes and uniform sizes from 3 mu m down to 600 nm. Three different proteins-lysozyme, thaumatin, and glucose isomerase-were crystallized as model systems to demonstrate the generality of this technique. Different polymorphs were formed simply by controlling the evaporation conditions.