The highly electropositive s-block elements combine with nitrogen in the solid state to form some of the most ionic nitride compounds known. Also, however, these elements can combine in binary and higher systems to form compounds with partially covalent character, predominantly metallic bonds or low dimensional structural hybrids of metallic and ionic components. The crystal and coordination chemistry of both binary and ternary s-block nitrides is unusual and provides the basis for unexpected and exploitable physical properties and a range of exotic reaction chemistry.