The paper operationalizes the concept of identity conversion to account for the process of becoming an audit partner in a Big 4 Firm. So far, literature has sought to document the identity construction of auditors based on field auditors or managers, overlooking the population of partners. The interactionist concept of career enables us to consider cooption as the turning point of a process that began the first day at work, and continues throughout the individual's career inside the firm. Through 25 life stories and 16 in-depth interviews, we show that auditors need an identity conversion to become partners, both from an individual perspective and through other auditors' eyes. It requires from them to solve conflicting expectations and to master informal ways of promotion, to finally complete the process of the making of a partner in a Big 4 Firm.