Luciferase reporter systems are widely employed to provide a quantitative readout of gene expression for studies of transcriptional regulation, translation efficiency, and cell signaling. The most common application of luciferase involves transient transfections into cells in vitro or in vivo. In both cases, the normal variability inherent in transfection approaches can introduce significant errors into the data that makes comparison between separate experiments problematic. The dual luciferase reporter assay system (DLR, Promega, WI, USA) is designed to control for this technical issue by using a co-transfection approach with two separate reporter proteins that emit at distinct wavelengths: one from firefly (Photinus pyralis ) and the second from Renilla (Renilla reniformis ). By normalizing experimental luciferase readings to an internal control transfected under the same conditions, these problems can be largely negated. Here, we describe a method for applying this technique to an in vivo system, the developing chick embryo neural tube. This system provides a physiologically relevant context for functional studies in a spatially and/or temporally controlled manner.