Previous research has examined call center agent performance from the viewpoint of efficiency (an organizational goal) or from customer satisfaction (the callers‘ goal). However, few studies examine call center practice from the perspective of the agent and caller by considering the text of interactions between them. The study takes a grounded theory approach to investigate the communication strategies of call center agents at a large company in Singapore receiving calls seeking information and solutions for problems. An initial list of strategies used in calls with customers was derived from an initial sample of 75 calls. These were discussed and refined with call center agents and managers. A large corpus of 1560 calls was then sifted for calls indicating customer-induced social stress factors. These calls were scored for efficiency, courtesy and effectiveness and the results analyzed in terms of communication strategies or conversational moves. Ten key communication strategies emerged that could be categorized into two broader constructs: solidarity building and conversational control. Hierarchical modeling analysis was conducted with a nested model including demographic variables and emotional intelligence, communication competence and cultural orientation of the agents in addition to solidarity building and conversational control strategies. Results showed that solidarity building predicted courtesy, conversational control strategies predicted efficiency, and both solidarity building and conversational control predicted effectiveness. Further, conversational control strategies had a negative effect on courtesy, while solidarity had no significant impact on efficiency. Implications for future research and practice are discussed.