Background: The relationship between early attachment experiences and longer-term outcomes continues to attract interest. Support to enhance attunement in relationships is often offered through early intervention, including the use of Video Interaction Guidance (VIG). There is a growing evidence-base for VIG's effectiveness, but its longer-term outcomes are unclear. This thesis explores current research and practice in relation to VIG's longer-term outcomes. Methods/ participants: Paper one describes a systematic literature review (SLR) which investigates VIG's effectiveness, particularly in the longer-term. The search was structured using PRISMA; it evaluated studies' methodological quality, appropriateness and relevance of focus, as well as reported outcomes. Paper two reports a two-part empirical study. Findings from the SLR were discussed in a focus group of 11 VIG practitioners from a range of roles. Key concepts were then identified through thematic analysis and used to devise a questionnaire. This was completed by 26 VIG-trained Educational Psychologists (EPs); responses were categorised using content analysis. Analysis/ findings: The SLR identified nine studies, of which six included follow-up measures. 22 different outcome measures were used across nine studies, highlighting the need for more homogeneity in the conceptualisation and measurement of outcomes. Findings from paper two suggest there are opportunities for developing practice, training and research in relation to the maintenance and monitoring of VIG's longer-term outcomes. Conclusion/ implications: Opportunities for the development of VIG training, practice and research are discussed, including applications within the context of educational psychology. In paper two, a model of VIG delivery is proposed, which incorporates findings relating to maintenance effects. Complexities relating to the conceptualisation and measurement of longer-term outcomes are discussed. A dissemination strategy is presented in paper three.