Following the implementation of the Youth Justice and Criminal Evidence Act 1999 for England and Wales, Registered Intermediaries have been available to assist child witness communication in legal proceedings since 2004. Registered Intermediaries are given training to fulfil this role. However, their assessments and practices are conducted independently. This study examined Registered Intermediaries’ perceptions and experiences of this independent practice, and the impact this had on the quality of the legal process in terms of evidential quality, child witness experiences and engagement. Seventeen experienced and currently active Registered Intermediaries with a range of communication specialisms took part in semi-structured interviews, which were analysed thematically. Six main themes emerged from the data: assessment constraints and requirements, essential elements of the assessment process, why the assessment process is effective, ensuring recommendations are followed through, pressures and barriers, and practice development. The Registered Intermediaries stressed the need for further training for themselves as well as for legal professionals, and emphasised the benefits of working as a team throughout the assessment and legal process.