This chapter will outline the main perspectives of the empirical study of competence and expertise in both translation and interpreting. We will cover such core issues as definitions and models of competence and expertise, the relationship between professionalism and expertise, and the multivariate nature of translation/interpreting expertise (cognitive vs. social), as well as the structure of deliberate practice in the field, the stages of competence/expertise acquisition, and how these stages can relate to training and professional experience. The chapter considers both exclusive and inclusive models of competence and seeks to critically link them to expertise. Furthermore, the chapter provides a survey of the methods employed to study the specific skills and knowledge included in these models. It will also consider areas that have received little attention to date in translation process research, namely, the role of selfregulation (motivation, metacognition, emotion regulation) in performance and in supporting deliberate practice. We conclude by outlining outstanding issues for further research as well as the implications of current research for the interpreting and translation professions.