To date, only 1 study has evaluated the impact of a Pavlovian drug conditional stimulus (CS) on operant responding. A within-subject operant 1-lever go/no-go (across sessions) design was used to evaluate the impact of Pavlovian contingencies on the discriminative stimulus effects of nicotine (0.4 mg/kg) and ethanol (800 mg/kg) in male Sprague Dawley rats. Drugs were administered 10 min before each acquisition and test session. One drug predicted sessions of food reinforcement and the other drug predicted sessions of nonreinforcement; stimulus roles were counterbalanced. In Experiment 1 (n = 7), operant lever pressing was initially maintained on a VI-30 s schedule of food reinforcement. This phase was followed by 20 (CS+ vs. CS-) Pavlovian drug discrimination training sessions without the levers present. Two extinction tests revealed significantly more operant lever pressing under the CS+ drug conditions compared to the CS- drug conditions, suggesting evidence for Pavlovian-instrumental transfer. Operant training significantly strengthened stimulus control. In Experiment 2 (n = 7), the drugs functioned as operant drug discriminative stimuli first. Next, the predictive roles of the drug [S[superscript D]s and [S[superscript[delta]]]s were reversed under Pavlovian CS- and CS+ contingencies, respectively. The original stimulus control was significantly undermined but was not reversed. These studies suggest that Pavlovian drug-reinforcer contingencies embedded within the operant 3-term contingency may play a partial role in mediating the discriminative stimulus effects of drugs. (Contains 2 tables and 1 figure.)