Despite numerous research studies on the antecedents of customer citizenship behavior (CCB; activities that customers voluntarily perform to help the firm and other customers, customers' role identity transitions remain unexplored as a possible antecedent in services marketing research. Previous research in customer co-production has shown that CCB increases service quality, customer satisfaction, and customer loyalty. Therefore, understanding why some customers may perform higher levels of CCB than others is important. Using role salience theory, this dissertation contributes to the CCB literature by investigating the influence of customers' role identity transitions (i.e., gaining role identities vs. losing role identities) on CCB. Furthermore, it attempts to explain these effects by examining two mediating processes. First, increased life stress is proposed as a consequence of customers’ role identity transitions. Second, drawing from psychological stress and coping theory, it is proposed that customers employ distinct coping functions (i.e., problem-focused vs. emotion-focused coping) to reduce the effect of life stress they experienced. Lastly, this dissertation predicts that CCB is a way for customers to cope with their life stress. Using structural equation modeling, this dissertation provides support for the proposition that customers who experience role identity transitions are more likely to perform CCB than customers who do not. The results also support the proposition that customers who experience role identity transitions tend to have increased life stress and that customers who lose their role identities tend to have more life stress than those who gain role identities. Contrary to the proposition, customers were found to use emotion-focused coping rather than problem-focused coping when faced with both types of role identity transitions. As predicted, CCB is shown as a way for customers to cope with life stress resulting from role identity transitions.