Dow AgroSciences has developed a synthetic gene (aad1) that increases selectivity of the phenoxyacetate and aryloxyphenoxypropionate (“fop”) herbicides for in-crop use in maize by metabolic detoxification. This gene has been introduced into maize (Zea mays L.). In this presentation, we describe the Enlist herbicide tolerant trait development in maize, including event selection and multi-generation molecular characterization and plant agronomic performance in the field.  The aad1 gene was introgressed into Mycogen elite inbreds from selected donor events. Hybrids made from converted aad1 inbreds expressed the target protein at levels that protected the maize from yield loss due to 2,4-D injury. Protection or tolerance was observed from the early seedling stage up to the reproductive stage at application rates exceeding 4 times typical herbicide use rates.  In contrast, the check hybrids had 10-20% yield loss due to 2,4-D injury. Enlist technology can also enable selective use of new formulations of 2,4-D in combination with glyphosate to provide increased control of broadleaf weeds in glyphosate tolerant corn.