$R_{c}$ measurements at LEP

The partial width $R_c = \Gamma(Z \to c\overline{c})$/$\Gamma(Z\to q\overline{q})$ is a basic observable in Z physics. Within the Standard Model its value is accurately predicted and other experimental measurements at LEP involve its knowledge. The DELPHI and OPAL collaborations have presented several Rc measurements. All methods are based on charmed hadron reconstructionand b/c separation. The LEP average, computed by the LEP Electroweak Heavy Flavor Working Group, is presented to be 0:1596 +- 0:0074. This is 1:8 standard deviation below the Standard Model expectation.