The present invention provides methods of making a population of nucleic acid molecules, wherein each nucleic acid molecule comprises a predetermined nucleic acid sequence, each of said methods comprising the steps of: (a) synthesizing, on a substrate, a population of nucleic acid molecules wherein: i) each synthesized nucleic acid molecule comprises a predetermined nucleic acid sequence; and ii) each synthesized nucleic acid molecule is localized to a defined area of said substrate; (b) harvesting said population of synthesized nucleic acid molecules from said substrate to yield harvested nucleic acid molecules; and (c) introducing said harvested nucleic acid molecules into vector molecules.