Uniquely among the amino acids, the sublimation of serine occurs with a strong preference for release into the vapor phase of a homochiral magic number cluster, the serine octamer. The strong homochiral preference for octamer formation is not reflected in the higher clusters of serine; however, they fragment with a strong preference to yield homochiral octamers. Other amino acids do not share these properties to a significant extent. The enantiomeric excess of serine can be increased in an experiment in which multiple steps of sublimation are used. The serine octamer also undergoes chirally-selective amino acid substitution reactions with other amino acids. The structure of the serine octamer is discussed with new data on the dissociation of higher clusters and with the aid of calculations on clusters of varying size and enantiomeric composition.