During development, the definitive endoderm differentiates into several gastrointestinal epithelial lineages, including enteroendocrine cells. The enteroendocrine lineage consists of at least 15 different cell types that are categorized based on their morphology, location and peptide hormone expression. The mechanisms regulating enteroendocrine cell differentiation are likely to be critical not only in embryonic development, but also during the constant renewal of gut epithelia in the adult. The identification of transcription factors and regulatory DNA elements required for cell type-specific gene expression in various endocrine cell types has broadened our understanding of the regulatory networks controlling the spatial and temporal activation of enteroendocrine differentiation programs. This chapter will review recent studies of transcription factors during enteroendocrine cell differentiation, with a focus on the central role for the Notch signaling pathway in enteroendocrine cell fate decisions.