Recent advances in genome engineering provide newfound control over a plant's genetic material. It is now possible for most bench scientists to alter DNA in living plant cells in a variety of ways, including introducing specific nucleotide substitutions in a gene that change a protein's amino acid sequence, deleting genes or chromosomal segments, and inserting foreign DNA at precise genomic locations. Such targeted DNA sequence modifications are enabled by sequence-specific nucleases that create double-strand breaks in the genomic loci to be altered. The repair of the breaks, through either homologous recombination or nonhomologous end joining, can be controlled to achieve the desired sequence modification. Genome engineering promises to advance basic plant research by linking DNA sequences to biological function. Further, genome engineering will enable plants' biosynthetic capacity to be harnessed to produce the many agricultural products required by an expanding world population.