The present invention provides compositions and methods for targeting recombinant retroviral particles specifically to cells of interest for delivery of desired therapeutic or toxic agents. The invention provides chimeric nucleotide constructs, chimeric proteins formed of a selected viral envelope gene from which a selected sequence has been deleted and into which has been inserted all or an effective portion of a heterologous ligand, said ligand or portion thereof capable of binding to a selected receptor, recombinant viral particles formed of the chimeric proteins, a biological mediator for delivery to the target cell; and retroviral gag and pol proteins. The lack of retroviral nucleic acid renders the viral particle replication defective and non-pathogenic.