Studies over roughly the last decade have emphasized the importance of gene expression in the development of structure and function of the songbird forebrain. However, few tools have been available to efficiently identify the critical factors. To that end, we have produced a normalized cDNA library from juvenile zebra finch telencephalon, and have spotted inserts from 2400 randomly selected cDNA clones on microarrays (1664 unique sequences). We have also added several previously cloned cDNAs of interest, including three representing genes encoded on sex chromosomes. Hybridizations comparing Cy3- and Cy5-labeled cDNA from the telencephalon of day 25 male and female zebra finches confirmed sexually dimorphic expression of the Z- and W-linked genes, demonstrating the utility of these microarrays for detecting differential expression and providing information about the relative expression of these genes in the brains of juveniles of this age.