Background: Development programmes to support newly qualified practitioners gain confidence in their first professional role often show varied levels of engagement, due to competing priorities and demands. In Scotland, the Flying Start NHS® programme uses a structured programme of online and work-based learning with associated mentoring, to support individuals through an often difficult transition to become capable, confident practitioners. Whilst the programme was generally well received, the factors leading to widely varying completion rates between professions and organisations were not well understood. Aim: The aim of this study was to identify the factors leading to successful completion of Flying Start, a transition programme for newly qualified practitioners. Method: A qualitative approach was adopted to gather data from two groups of participants. Semi-structured telephone interviews were conducted with strategic and management level participants (n = 23), from five health boards in Scotland. Semi-structured interviews (n = 22) and focus groups (n = 11) were conducted with practitioners within 6 months either side of completing the programme. The interviews were transcribed and analysed using framework analysis. Results: Three key themes relating to successful completion emerged from the analysis: Management and Delivery; Content and Material; Participation and Completion. Factors leading to successful completion were identified at programme, organisational and individual levels. These included clear communication and signposting, up-to-date and relevant content, links with continuing professional development frameworks, effective leadership, mentor and peer support, setting clear standards for assessment, and facilitating appropriate IT access. Conclusions: A strong strategic commitment to embedding a development programme for newly qualified practitioners can ensure that the necessary support is available to encourage timely completion. The mentor's role - to provide face-to-face support - is identified as a key factor in completion and is achieved through setting attainable targets, monitoring progress, and providing motivation. However organisational structures that facilitate the mentoring relationship are also necessary.