You all may have found this one out even earlier, but I found this out just a few days before. A WCF Service doe not allow normal method overloading , which is supported by .NET. It throws InvalidOPerationException. As for the reasons to why this happens is becasue WSDL is not a object orinted language and does not support these features of OOP. However overloading can be performed in WCF service in a roundabout way. [ServiceContract] interface ICalculator { [OperationContract(Name="Ad...