This article presents the findings of a survey of sign language interpreters’ perceptions of the skills, knowledge and abilities required for effective practice. Specifically, practitioners were asked to rate the degree of importance of some of the identified key skills, knowledge and abilities for professional practice based on the literature, and then rate their own degree of competence as a practitioner on the same parameters. Furthermore, interpreters supplied an overall rating of competence, based on their perception of their own performance as a practitioner. A skills gap analysis was conducted to determine the significant differences between ratings of importance and ratings of competence on each of the skills, knowledge and abilities documented. This yielded information with regard to the most critical skills, knowledge and abilities perceived by sign language interpreters, and clearly identified gaps in competence among practitioners. Interpreter accreditation level emerged as a significant dimension in the context of self-reported level of competence and skill for sign language interpreters. Such findings have important implications for the education and training of sign language interpreters, and repercussions for ongoing professional development and self-monitoring by practitioners.