This study attempts to integrate social exchange theory (SET) and social representations theory (SRT) in understanding residents’ perception changes throughout a mega-event’s full life cycle. A three-wave survey approach was employed to track local residents’ evolving attitudes toward the 2010 Shanghai Expo. Results showed that Shanghai residents’ perceived impacts at the community level were more positive than at the individual level. Residents’ visit status (i.e., whether they attended the event or not) did not appear to substantially influence their perceptions of impacts at either level, albeit attendees did demonstrate more favorable attitudes on several aspects. Most residents held similar perceptions at the beginning of and six months after the Expo had concluded, but their perceptions at the Expo’s conclusion were the most negative. This study supports that SET and SRT are distinctly operative in different contexts but can complement each other in explaining residents’ perception changes.