Many genes are required to assemble flagella. These genes encode not only the structural elements of the flagellum but also a number of regulators that control how the flagellar genes are temporally expressed during the assembly process. These regulators also specify the likelihood that a given cell will express the flagellar genes. In particular, not all cells express the flagellar genes, resulting in mixed populations of motile and non-motile cells. Nutrients provide one signal that specifies the motile fraction. In this chapter, we describe two methods for measuring flagellar gene expression dynamics using fluorescent proteins in Salmonella enterica. Both the methods can be used to investigate the mechanisms governing flagellar gene expression dynamics.