This chapter reviews the literature published during 2011 relating to the above area, apart from a few papers from 2010 in less accessible journals which came to light in Chemical Abstracts in 2011. Synthetic routes to phosphines are reported, together with studies of their reactivity towards various atomic and molecular electrophilic sites involving carbon, halogen, boron, nitrogen and other acceptors. Also reported are studies of developments in the chemistry of low coordination number p_π-bonded phosphorus compounds and related potentially aromatic heterocyclic phosphorus systems.