This study examines psychological resources for service employees and their customers, which enhance the service experiences of both parties during service conversations. We investigate whether customer behaviour (customer-initiated support) positively impacts on employees’ affect. We also examine the crossover of employees’ affect on customers’ affect. State positive affect (PA) was assessed in 82 employees of car dealerships and 421 customers on 2 occasions (before and after the conversation). Multi-level analyses showed the hypothesized positive impact of customer behaviour on employees’ PA and in turn of employees’ PA on customers’ PA. Results are integrated in an overall process model whereby customers’ PA leads to customer-initiated support, which increases employees’ PA and in turn enhances customers’ PA. Results suggest direct and indirect crossover effects. This study extends research on customer behaviour offering a positive slant on customer behaviour and suggests to actively involve customers in the service process in order to promote their positive behaviour towards employees.