The purpose of this study is to consider the dynamics of customer education via investigating relationship between customer’s education and expertise and their combined effects on customer’s loyalty in investment services requiring high participation in active brokerage firms of Tehran Stock Exchange.This paper provides a conceptual model consisting of research objectives, as a series of testable hypotheses. Based on survey results, customer loyalty has positive and significant relationship with technical service quality (first hypothesis), functional service quality (second hypothesis), and customer training (third hypothesis). However, contrary to expectation customer expertise had not negative relationship with customer loyalty (fifth hypothesis). According to study findings client training was correlated positively with customer expertise (fourth hypothesis). The main effect of customer training on loyalty was statistically significant, however, this subject was not disappeared when client expertise entered third equation. Finally, positive significant interaction coefficient between technical service quality and expertise indicates that positive effect of technical service quality on customer loyalty was indeed stronger when customer’s expertise was high (sixth hypothesis). In contrast, and consistent with predictions, the relationship between functional service quality and customer expertise was significant and negative, which indicates a positive relationship between functional service quality and customer loyalty,while increasing customer expertise decreases (seventh hypothesis).