Hapten-carrier conjugates capable of eliciting anti-hapten antibodies in vivo by administering, in a therapeutic composition, are disclosed. Methods of preparing said conjugates and therapeutic compositions are also disclosed. Where the hapten is a drug of abuse, a therapeutic composition containing the hapten-carrier conjugate is particularly useful in the treatment of drug addiction, more particularly, cocaine addiction. Passive immunization using antibodies raised against conjugates of the instant invention is also disclosed. The therapeutic composition is suitable for co-therapy with other conventional drugs.