All significant experimental measurements and many theoretical calculations of the spectroscopy and structure of the isotopic lithium hydrides (6LiH,7LiH,6LiD,7LiD) are identified and reviewed. Published molecular constant determinations from conventional and laser spectroscopy are evaluated; recommended spectroscopic constants for theX 1&Sgr;+,A 1&Sgr;+, andB 1&Pgr; states are tabulated. Potential energy curves (RKR, IPA, and hybrid) for theX 1&Sgr;+,A 1&Sgr;+, andB 1&Pgr; states are evaluated and recommended curves are tabulated. Dissociation energy estimates are evaluated and recommendedD0andDevalues tabulated forX 1&Sgr;+,A 1&Sgr;+, andB1&Pgr; states. Accurate electronic structure calculations (Hartree Fock or better) on this ‘‘workbench of theoretical chemistry’’ are listed and described briefly; all excited electronic states considered are included. Experimental and theoretical radiative and dipole properties are noted and discussed. Adiabatic corrections to the Born–Oppenheimer approximation are also reviewed. Calculations on LiH+and LiH−are also listed and described briefly.