The Relational Approach to group work was developed during the UK-based Social Pedagogic Research into Group-work project (SPRinG). The Approach is built upon the premise that children will need support to ensure they can engage in, and benefit socially and cognitively from interactions with their peers. The SPRinG research found that, in schools where the Relational Approach was developed, there were positive gains for teachers and pupils, including: increased pupil-peer cooperation; widening of pupils' social networks; and improved pupil attainment in reading and Mathematics. This thesis adopts a social constructivist methodology to explore the development of the Relational Approach to group work with children aged thirty to sixty months within one pre- school. A number of data collection tools, including interview, sociometry and video recording, were employed to explore the development of the Approach and its impact on children's peer interactions, and on practitioner pedagogy and practice. Data were analysed utilising an appropriate combination of qualitative and quantitative methods, for example content analysis of video data. A major finding of this research is that developing the Relational Approach to group work within the pre-school led to changes in practitioner pedagogy and practice, which positively impacted upon the development of children's social competencies. Using the example of the Relational Approach to explore the role of the pre-school practitioner, a series of five mediating factors are identified which together provide a framework for practitioner pedagogy and practice to support the development of children's social competencies. These five factors are that practitioners should: understand the theoretical and conceptual underpinnings of relational programmes and activities; provide a suitable setting in which positive relationships and the development of social competencies can thrive; reflect upon their practice and observe children's behaviours and use the knowledge gained to develop their practice accordingly; hold expectations that the children are capable of developing social competencies and make these expectations explicit; and model the desired social competencies to children. The framework provides a useful guide for all practitioners working with young children, particularly those who wish to improve the quality of their practice and for those who wish to ensure children benefit socially and cognitively from interactions with their peers.