Publisher Summary This chapter focuses on two genomic approaches that have been used recently in laboratory to identify additional nuclear hormone receptor (NR) target genes—that is, the serial analysis of gene expression (SAGE) and gene trapping. Because the success of these differential gene expression (DGE) approaches depends to a large extent on the experimental study design, the chapter describes the different strategies used to change NR activity. Nuclear hormone receptors (NRs) form a family of transcription factors that regulate the expression of target genes in response to binding small, lipophilic ligands such as hormones, nutrients, as well as endo- and xenobiotic metabolites. In addition to these receptors, a large number of proteins have been identified that share many of the structural features of nuclear hormone receptors, but lack identified ligands. The gene trapping method is a cell-based approach that uses random insertion of a promoter less reporter gene into the host cell genome. In case the reporter gene has been integrated into a NR target gene, a change in reporter expression is observed in response to NR activation.