Organic nonlinear optical materials are difficult to prepare in single-crystalline form due to the inhibition of growth by the solvent. This yields poor growth characteristics which result in the development oi. strain and inclusions in the grown crystal. A study has been made of the growth mechanism and morphology of N-(4-nitrophenyl)prolinol using both a polar and nonpolar solvent. The results are used to define conditions for the preparation of large crystals up to 2 x 0.8 x 0.8 cm(3) of exceptionally high optical and structural perfection.