This chapter outlines seven synthetic and molecular biology techniques that allow the controlled synthesis of nucleic acid libraries. Specifically: (1) The high-diversity chemical synthesis of point mutations; (2) the high-diversity chemical synthesis of point deletions; (3) the split-bead approach for constructing point mutation or deletion libraries with limited sequence diversity; (4) pool deprotection, gel purification, and quality-control techniques; (5) large-scale polymerase chain reaction amplification for the generation of high-diversity double-stranded deoxyribonucleic acid libraries; (6) type II restriction enzyme digestion techniques for the construction of long-sequence libraries containing minimal fixed sequence; and (7) extension techniques for the rapid synthesis of long, low-diversity oligonucleotide sequences.