Purpose: This paper seeks to explain how auditors' professional and organizational identities are associated with commercialization in audit firms. Unlike previous studies exploring the consequences of commercialization in the firms, our study directs its attention toward the potential driver of commercialization, which we argue to be the identities of the auditors. Design/methodology/approach: The paper is based on 374 responses to a survey distributed to 3588 members of FAR, the professional association of accountants, auditors and advisors in Sweden. The study used established measures of organizational and professional identity and introduced market, customer and firm process orientation as aspects of commercialization. The study explored the data through descriptive statistics, principle component analysis and correlation analysis and tested the hypotheses with multiple linear regression analysis. Findings: The findings indicated that the organizational identity of auditors has a positive association with three aspects of commercialization: market orientation, customer orientation and firm process orientation. Contrary to the arguments based on prior literature, our study has found that the professional identity of auditors is also a positively associated with commercialization. This indicates a change of the role of professional identity vis-à-vis commercialization of audit firms. The positive association between professional identity and commercial orientation could indicate the development of "organizational professionalism." The study also found differences between the association between professional identity and commercialization in Big 4 and non-Big 4 firms. While in Big 4 firms, professional identity is positively associated only with the firm's process orientation, in non-Big 4 firms, professional identity has a positive association with all three aspects of commercialization. Originality/value: The paper provides insight into how auditors' identities have influenced commercialization of audit firms and into the normalizing of commercialization within auditing. The study also developed a new instrument for measuring commercialization, one based on market, customer and firm process orientation concepts. This paper suggests that this instrument is an alternative to the observation through proxies.