Teacher recruitment and retention is an international challenge. In England the government have reported that more teachers leave before retirement age than five years ago, 30% within five years and schools are finding it difficult to fill posts with quality teachers . This paper evaluates the contribution of the research-informed RETAIN Early Career Teacher (ECT) Continuing Professional Development (CPD) Programme for developing and retaining quality teachers. RETAIN was a yearlong CPD pilot for Early Career Teachers (ECTs) in primary schools in Cornwall, UK (a region with high levels of socio-economic disadvantage). The programme design was informed by research and based on factors shown to support the retention of ECTs. It was contextualised using the precept that teachers should be active researchers, influencing curriculum development as 'reflective practitioners', focussed with a Professional Learning Community lens and theorised within a social constructivist frame. In addition, RETAIN utilised robust evidence-informed practice approaches to support teacher development in schools with persistently disadvantaged pupils. The programme was independently evaluated using multiple-methods over the course of the programme to generate data. The theory-based evaluation suggests that the contribution of this intervention to the field is the specific combination of development; taught workshops, coaching and collaborative professional learning, which improved the self-efficacy, confidence and quality of teaching of ECTs in differing but complementary ways. All ECTs who completed the programme have been retained in teaching and all have achieved a leadership role in their school. We argue that these outcomes are of international significance and the promise of the programme can be utilised for developing and retaining high quality teachers in other countries.