Competence is not a static construct, it develops over time, first through training and then through work experience (see Albl-Mikasa, 2012 and Albl-Mikasa, 2013 for details on the development of interpreting competence). In Interpreting Studies, the development of competence has received limited research attention, however, there are several studies focusing on expertise in interpreting. This chapter first surveys models of the development of translation competence, then summarises results related to the development of expertise in interpreting.