Conjugates of a hydrophobic moiety, such as a lipid, linked through a cleavable dithiobenzyl linkage to a therapeutic agent are described. The dithiobenzyl linkage is susceptible to cleavage by mild thiolysis, resulting in release of the therapeutic agent in its original form. The linkage is stable under nonreducing conditions. The conjugate can be incorporated into liposomes for administration in vivo and release of the therapeutic agent in response to endogeneous in vivo reducing conditions or in response to administration of an exogeneous reducing agent.