Natural products are an unsurpassed source of chemical diversity and an ideal starting point for any screening program for pharmacologically active small molecules. Historically, natural products have been the most successful source of new drugs. The Screen-Well® natural product library offers over 500 isolated natural compounds of known structure and includes many compounds from ethnopharmacology. Compounds are provided in solution in DMSO. Individual compounds or subsets can be resupplied in gram quantities.