Purpose – The purpose of this paper is to understand the influence of leadership programmes on leaders and co-workers, as well as which mechanisms are involved in the process.

Design/methodology/approach – An analysis was done into 431 free-text answers to questionnaires given to 120 participants in two different leadership programmes and their co-workers six months after their participation, using a grounded theory inspired approach.

Findings – The result is a model, linking internal psychological and external behavioural aspects, with the central outcome that leaders gained more confidence in their leadership role through theoretical models learned, and reflection.

Research limitations/implications – The course participants as well as the co-workers seemed to experience a positive leadership development indicating a value of participating in the courses.

Practical implications – Confidence in leadership role seems important for having positive outcomes of leadership. Although this needs further research, it is something organisations should consider when working with leadership questions.

Social implications – The co-workers perceived their leaders to be calmer, more open for discussions, and willing both to give and receive feedback post training. There appears to be an increase in trust both in the leader and reciprocally from the leader in the co-workers.

Originality/value – Until now there has not been any systematic research into the effects on participants and co-workers following the programmes, despite the fact that over 100,000 have participated in the courses.