Professional learning is a key driver for improving the use of evidence-based practices in education. However, participating in high-quality external professional learning requires a significant investment of time and resources, which can be challenging for under-resourced or minimally staffed educational settings. A peer mentoring approach to professional learning is one way to resolve this challenge. It involves a small number of staff completing external professional learning and sharing what they learnt with colleagues who did not attend. This approach to professional learning is common practice in many workplaces. While some workplaces may have an organised approach to peer mentoring, others may expect it to happen organically. This study investigated the feasibility and impact of peer mentoring for sharing skills and knowledge from professional learning, in comparison to an approach where all or most teachers and educators receive external professional learning. The authors conducted the study in early childhood education and care (ECEC) services with educators and teachers who worked in preschool rooms. The external professional learning focused on providing ECEC educators and teachers with the skills and knowledge to use evidence-based oral language and early literacy practices. [This report was co-produced with the Australian Literacy and Numeracy Foundation.]