Described herein is a recombinant respiratory syncytial virus (RSV) having an attenuated phenotype. In one embodiment, recombinant RSV includes an M2-2 protein with a mutation that renders the M2-2 protein inactive or prevents expression of the M2-2 protein. In one embodiment, the amino acid at position 66 in the F subunit has a positively charged side chain. Nucleic acids encoding recombinant RSV are also described, as well as vectors containing the nucleic acids.