The present invention provides recombinant respiratory syncytial viruses that have an attenuated phenotype and that comprise one or more mutations in the viral P, M2-1 and/or M2-2 proteins, as well as live attenuated vaccines comprising such viruses and nucleic acids encoding such viruses. Recombinant RSV P, M2-1 and M2-2 proteins are described. Methods of producing attenuated recombinant RSV, and methods of quantitating neutralizing antibodies that utilize recombinant viruses of family Paramyxoviridae, are also provided.