This thesis outlines a self-study action research project which follows my journey of developing the vocabulary and expressive language skills of my junior infants class in an urban co-educational Dublin school. I decided to devote this action research journey to the development of oral language skills through play as a result of my core teaching values and my own school experience. Having been lucky enough to experience a teacher who taught through playful methodologies, this experience is something which has followed and directed me through my initial teacher education and early career. My core teaching values are centred upon respect, trust, compassion and creativity. Thus, I wanted to engage in an action research project which was not only personal to me, but which allowed me to develop my practice and teach in a way which was representative of these values. With the introduction of the new Primary Language Curriculum in 2019, which is open to and inclusive of playful methodologies, I felt it important to highlight the multitude of benefits that result from these playful methodologies in relation to children’s learning and, in particular, on their oral language skills. I designed a playful, evidence-based and cross-curricular intervention for teaching vocabulary and expressive language skills through play in my junior infants classroom. The intervention had three key components: the integration of play into two specific curricular areas – Literacy and Social, Environmental and Scientific Education (SESE), pre-teaching vocabulary alongside the use of stories and the use of the early childhood Aistear framework. Action research was chosen as the methodology for the study as it enabled me to critically examine my own practice while also enhancing it. Throughout the action research process, I collected a large amount of both qualitative and quantitative data through the use of the following data collection instruments: a reflective journal, student-teacher conferencing, teacher observations, samples of my students’ work, vocabulary checklists, an expressive language rubric, my own original data collection tool - the ‘Highlights Chair’ and feedback from a critical friend. My engagement with the reflective process enabled me to generate a living theory. This living theory then allowed me to identify the ways in which I could align my practice more closely to my values. The findings that emerged from this study were centred upon: • Collaborative learning as a way to extend vocabulary and expressive language • The impact that enjoyment has on the development of vocabulary and expressive language skills • The role of adults in expanding children’s vocabulary and expressive language skills Playful teaching methodologies can have a profound impact on children’s learning as a whole, but particularly in relation to the development of their oral language skills. As teachers, we owe it to our students to incorporate age-appropriate and child-led teaching methodologies which demonstrate active learning and an awareness of the individual needs of our students. The findings from this research showcase the vast benefits of including playful methodologies in the primary school classroom and highlight a successful three-part intervention for the introduction of play into the classroom. This research has also resulted in a significant change in how I approach the teaching of vocabulary and the development of my students’ expressive language skills and will continue to do so for years to come. Not only has it allowed me to align my practice with my core teaching values but it has also enabled me to teach in a way which is representative of my educational beliefs and positive school experience. Play comes naturally to children from a young age and I believe that it is our responsibility as teachers to promote this intrinsic concept which, when nurtured, can last a child’s whole life through.