The cohesin proteins compose an evolutionarily conserved complex whose fundamental role in chromosomal cohesion and coordinated segregation of sister chromatids has been well characterized across species. Recently regulators and structural components of cohesin have been found to surprisingly cause specific human developmental disorders (collectively termed “cohesinopathies”) and some cancers when mutated. Since the first report of cohesin's role in regulating gene expression 10 years ago, there has been an explosion of literature implicating cohesin in multiple diverse cellular and gene regulatory processes. While downregulating cohesin sufficiently to cause significant sister chromatid cohesion defects is universally lethal to multicellular organisms, the mechanism of action by which cohesin effects developmental processes appears to be through a non-canonical role as a regulator of gene expression. It became evident that there was a need to bring cohesin basic scientists together with clinical investigators interested in the medical disorders associated with cohesin dysfunction to cross pollinate their fields and advance both the basic biology as well as the understanding of, and improved treatments for, this newly classified group of clinical disorders. Towards this end an international meeting hosted by the CNR in Italy and jointly supported by funds from the CdLS USA Foundation and the National Institute of Child Health and Development (NIH) was established in 2007. Based upon the success of that meeting a standing biennial meeting was established and the proceedings from the Second International Cohesin Biology and the Cohesinopathies Biennial Meeting held in Pontignano, Italy in 2009 are presented here. © 2010 Wiley-Liss, Inc.