Children in their early childhood years have proven to be capable of becoming active citizens in their communities through engagement in sustainability practices, with the support of their teachers. However, EfS is currently not widespread within the early childhood sector and tends only to be implemented in centres by teachers who are passionate about sustainability. This thesis examines the perceptions of how a cohort of pre-service early childhood teachers, who completed an EfS paper in their final year of teacher education, felt they had been prepared to teach EfS. It also examined how four new graduates from this cohort perceived their preparation to teach EfS when they began teaching. This research was undertaken in two phases and used a mixed method approach to collect qualitative and quantitative data. A questionnaire was used to collect data during phase one of the study. Open and closed questions were used to investigate student teachers’ conceptions of sustainability and the environment, their perceptions of the relationship between humans and nature, the role of the teacher when teaching EfS, teaching and learning in EfS, and confidence and motivation to teach EfS. Data gathered from the questionnaire were analysed using a thematic approach and simple statistical analysis. Data collection for phase two of the study was via interviews with four new graduates who were in the first four months of their teaching career. The interviews were semi-structured using open questions. Data from the interviews were analysed and categorised into three general sections – background of the centre, affordances of the centre for EfS and the graduates’ perceptions of their readiness to teach EfS within that centre. Findings showed that undertaking a paper in EfS in their final year of study had influenced the student teachers’ knowledge of sustainability, particularly in relation to protection of the planet. Student teachers felt that it was important for teachers to support young children to develop connections and sensitivity toward nature, and to support children to actively engage in sustainable practices to protect the environment. The majority felt it was important for teachers to have prior knowledge of sustainability issues in order to teach young children. All students felt a level of confidence and motivation to teach EfS on completion of the paper. However, despite feeling confident and motivated to teach EfS when beginning their employment in early childhood centres, the level to which the new graduates had actually engaged in EfS was influenced by the realities of being a new teacher and the value placed on EfS by the centre they were teaching in. All four graduates felt they would engage more with EfS once they felt more settled into their teaching roles. These findings suggest that if EfS is to become more widespread in the early childhood sector, then pre-service teacher education providers need to include dedicated EfS papers that provide a balanced approach to sustainability education within their teacher training programmes, and consider how new graduates can effectively incorporate their EfS learning into their teaching in their new positions.