We have taken unbiased genome-wide approaches to elucidate steroid hormone action. We coined the term "cistrome" to define the set of cis-regulatory targets of trans-acting factors across the entire genome. The analyses of steroid receptor cistromes combined with gene expression profiling data have revealed new insights into the organization of hormone-responsive genes and the existence of a transcription factor and epigenomic code that dictates cellular responses to steroid hormones.