Three theories about the effect of social mobility on attitude toward the political system are examined:cognitive dissonancetheory,tensiontheory, andacculturationtheory. Various measures of “attitude toward the system” that have been employed within these three theoretical contexts are discussed, and the appropriateness of political and personal efficacy scales is suggested. Using these scales to tap “attitude toward the system,” the relative efficiency of the three theories is assessed by fitting a dummy variable, additive regression model of origin and destination status effects to data obtained from a 1968 national survey. Mean efficacy scores predicted by the additive model are found to represent actual mean scores closely, resulting in the rejection of thecognitive dissonanceandtensiontheories which predict different forms of interaction. The mobility process itself has no unique effects on political or personal efficacy: rather, the mean efficacy of the mobile lies between that of origin and destination statuses, suggesting that mobile individuals become resocialized into their new status group.