A molecular sieve comprising crystals or agglomerates of average diameter 100 nanometers or less, which molecular sieve has a crystal or agglomerate size distribution such that the variance in the longest dimension is less than 15% of the average longest dimension, and which is capable of forming a collodial suspension, may be prepared by producing a boiling aqueous synthesis mixture of a silica source and an organic structure directing agent in the form a hydroxide in an amount sufficient to cause substantially complete dissolution of the silica source, and crystallizing the solution at 120° C. or less. The crystal size may be controlled by selection of an appropriate crystallization temperature.