The increased awareness of endocrine disrupting chemicals (EDCs) and their potential effects on wildlife and humans has produced a demand for practical screening methods to identify endocrine activity in a large number of environmental samples. While it is clear that in vivo methods will be required to identify adverse effects produced by these chemicals, in vitro assays can define particular mechanisms of action and have the potential for rapid and low-cost screening of large scale EDC screening programs. This presentation will address the trends and analytical challenges associated with the detection and quantitation of EDCs in various matrices.