The Drosophila nervous system provides a valuable model for studying various aspects of brain development and function. The postembryonic Drosophila brain is especially useful, because specific neuron types derive from specific progenitors at specific times. Elucidating the means by which diverse neuron types derive from a limited number of progenitors can contribute significantly to our understanding of the genetic and molecular mechanisms involved in developmental neurobiology. β-Galactosidase, the product of the E. coli lacZ gene, has been used extensively as a reporter in Drosophila research. Staining for β-galactosidase activity can be performed using the substrate X-gal (5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside), which produces a blue precipitate visible by light microscopy. This detection method is highly sensitive and has the advantage that the results can be observed without the need for specialized microscopy equipment. This protocol describes general procedures for X-gal labeling of neural tissue from Drosophila.