Abstract: Understanding the events controlling endosperm development and it’s genetic regulation may give new possibilities for molecular farming, functional foods and fish feed. The cereal endosperm represents the worlds major source for food, feed and industrial raw material. When fully developed, the endosperm is a simple plant system consisting of four major cell types, the starchy endosperm, the aleurone layer, the transfer cells, and cells of the embryo surrounding region. Our work in maize, rice and barley, is complemented with studies in Arabidopsis, with increasing opportunities with comparative genetics with the genome of Arabidopisis sequenced and rice to come. An understanding of the mechanisms underlying endosperm development in general and cell fate specification in particular, is expected to facilitate alterations in grain quality as well as quantity. Results from reverse approaches to identify regulatory control elements directing preferential endosperm expression in transgenic maize, rice and barley for different promoter regions (LTP1, LTP2, B22E and AGPase) will be discussed. When genes controlling cell identity are identified through mutant studies, genetic screens and transgene studies underway, this knowledge can be used to generate cereals to meet special needs.