The behavioral approach (BAS) and behavioral inhibition (BIS) systems are central to theories of both personality and psychopathology, yet agreement on methods of assessing BAS and BIS sensitivity has yet to emerge. We compare the Carver and White (1994) BIS/BAS scales with putative physiological markers of BAS (pre-ejection period [PEP], respiratory sinus arrhythmia [RSA]) and BIS (electrodermal responding) reactivity during reward and extinction among 50 undergraduates. PEP, RSA, and electrodermal activity each responded strongly to one or more task conditions, but correlations with BIS/BAS scores were stronger for measures of affectivity than for any physiological marker. Finally, PEP reactivity was the only autonomic index that responded only to reward. These findings suggest that (a) self-report and physiological measures of BAS and BIS reactivity are independent, and (b) PEP may be superior to RSA as an index of approach motivation.