This study explores teachers' experiences of peer observation in a post-primary setting. We begin by reviewing the literature on the peer observation of teaching, teacher professional development, professional learning communities and reflective practice. A qualitative, inductive, multi-method case study is used. Four pairs of teachers participated. A questionnaire, semi-structured interviews and reflective logs were used for data collection. The data were analysed thematically. The findings indicate that peer observation leads to reflective practice which consequently results in personalised learning for the participants. Peer observation appears to enhance staff collegiality, facilitates the emergence of a professional learning community and enhances individual teacher self-efficacy. This research concludes that teachers require supports to help them develop reflective skills. Additional research is required to explore the relationship between teacher reflection and continuous professional development.