While all cells in the body share the same genetic material in DNA, different cell types can turn different genes on or off by controlling the access to DNA. DNA is wound up like a spool with proteins in a complex called chromatin. Stem cells can choose and commit to different cell fates by carefully rearranging the organization of chromatin. Our research has shown that a new class of genes called long noncoding RNAs appear to have an important role in telling which genes stay on. This occurs by the RNAs talking to proteins that keep chromatin in an active configuration. We have also developed new methods to measure the location of open chromatin sites much more rapidly and sensitively than previously possible.