In the present Letter doubly resonant sum-frequency generation (DR-SFG) second-order polarizabilities (beta) are reported for the lithium hydride molecule. The calculations, which refer to the diagonal longitudinal component of beta and ignore rotation, are based on data evaluated using the multireference configuration interaction method with singles and doubles. The DR-SFG results are partitioned into their infrared-visible and visible-infrared components. They are analyzed as a function of the infrared and visible frequencies as well as the number of vibrational states considered in the sum-over-states expressions. (C) 2003 Elsevier B.V. All rights reserved.