The coordination of gene expression is critical for cell differentiation and the subsequent establishment of tissue function. We show here that a multiple zinc finger transcription factor, Zfp423/OAZ, is transiently expressed in newly differentiating olfactory-receptor neurons (ORNs) and has a key role in coordinating the expression of immature and mature stage-specific genes. OAZ deletion in mice impairs aspects of ORN differentiation, particularly the patterns of axonal projection to the olfactory bulb. OAZ gain-of-function experiments show that sustained OAZ expression throughout ORN maturation arrests ORN development at an immature stage and alters OR gene expression. Importantly, reintroducing OAZ expression in mature ORNs suppresses mature marker expression and reactivates immature-specific markers. Together, these experiments suggest that OAZ participates in a developmental switch regulating the transition from differentiation to maturation in ORNs.