In this paper we evaluate an action learning-based, leadership development programme designed for founders and leaders of growth-oriented, entrepreneurial small to medium-sized enterprises. Based on in-depth, qualitative interviews with participants on one cohort, undertaken two years after completion of the seven-month programme, we demonstrate that by viewing action learning as an ethos that informs practice, it can contribute to the process of effective leadership development with identifiable personal and business outcomes. (Contains 3 figures and 2 tables.)