Using Social exchange perspective, this study investigates the impact of High Performance Work Systems (HPWS) on employees‘ pro-change attitudes and behaviors (i.e., Commitment to change and behavioral support for change). It also endeavors to examine the underpinning micro-mechanisms of HPWS and employees‘ pro-change behaviors, suggesting that social & economic exchanges are the important mediating variables. Moreover, this study proposes an integrative moderated mediation model and posits that employees‘ cultural values (power distance and collectivism) moderate the aforementioned two alternative mediation mechanisms. Using random sampling technique, a sample of 591 full-time employees of largest public sector bank of Pakistan undergoing privatization are surveyed during September-December 2017. Proposed hypotheses are tested through Structural Model in AMOS. The results reveal that perceptions of social exchange partially mediate the positive relationship between HPWS –Affective CTC and HPWS-Normative CTC. On the other hand, perceptions of economic exchange fully mediate the HPWS- Continuance CTC.In addition, the relationship between HPWS-Affective CTC and HPWS-Normative CTC via social exchange is stronger for employees scoring high collectivism and low power distant orientation. Similarly, the relationship between HPWS-continuance CTC via economic exchange is stronger for employees scoring low collectivism and vice versa. However, the moderated mediated impact of power distance on HPWS-continuance CTC via economic exchange remained insignificant. In addition, the impact of CTC components on behavioral support for change is found to be statistically significant. In the end, practical and theoretical implications of HPWS- employees‘ pro-change reactions are discussed in the light ofresults.