Purpose: The purpose of this paper is to review some uncertainties experienced by a group of CEs, and how they are assuaged through their participation in an executive development (ED) programme. These uncertainties relate both to their involvement in the programme as such, particularly during their early days of membership, and to their everyday work experience. Design/methodology/approach: An in-depth, longitudinal case study of an ED programme undertaken by the authors, using participant observation, semi-structured interviews and documentary analysis. Findings: Five main CE uncertainties are identified: knowledge, job/career, behavioural, personal, and contextual. The case study section of the paper outlines each of these uncertainties, and illustrates how they are being assuaged through the CE programme. Research imitations/implications: The usual caveats apply about generalising from a case study. On the other hand, the paper presents a rare detailed "insider" account of and reflection upon chief executives' experience of an ED programme, situating it in the wider contexts of their work and anxieties. Practical implications: In the light of the uncertainties identified, a number of implications for the design and operation of executive development programmes are outlined and discussed. Originality/value: New data is presented and analysed, linked to relevant themes in the ED/Leadership Development literatures.