Chimeric human-bovine parainfluenza viruses (PIVs) are infectious and attenuated in humans and other mammals and useful individually or in combination in vaccine formulations for eliciting an immune response to PIV or other pathogens. Also provided are isolated polynucleotide molecules and vectors incorporating a chimeric PIV genome or antigenome which includes a partial or complete human or bovine PIV "background" genome or antigenome combined or integrated with one or more heterologous gene(s) or genome segment(s) of a different PIV. Chimeric human-bovine PIV of the invention include a partial or complete "background" PIV genome or antigenome derived from or patterned after a human or bovine PIV virus combined with one or more heterologous gene(s) or genome segment(s) of a different pathogen, including different PIV virus to form the human-bovine chimeric PIV genome or antigenome.