In this paper the evolution of assessment centres into the broader concept of development centres is discussed (Moses & Byham, 1982; Goodge, 1995; 1997). The implications of this learning emphasis shift are reviewed and examined in the context of a case study - the Centre for Individual Management Development (CIMD), designed with the Management Development Centre (MDC) to identify emerging leaders for the New Zealand Public Service (NZPS). The CIMD was endorsed and actively supported by the State Services Commissioner, current NZPS chief executives (as behavioural observers), and senior government ministers, former parliamentarians and media active national political journalists (as simulation role-players).The design and functioning of the centre is described in the context of the history and evolution of assessment centre technology (Thornton & Byham, 1982). The specific centre design is examined against the ‘three generation’ model proposed by Matheson and Evans (2001). Using this framework the authors propose that it be extended to include fourth generation design principles and the case study illustrates the need for this. In examining the "learning centre" concept underpinning the design, the authors draw on organisational learning and related literature (for example, Higgs, 2002; Wenger, 1998; Mumford, 1995; Revans, 1982; Schein, 1992), and explore the differences between building leader and leadership capability (the two strategic imperatives identified by the NZPS). The characteristics of such a design are described and illustrated by reference to the case study. The aim of the "learning centre" design is summarised as enhancing the senior manager learning which can result from participation in chief executive future role and organisational culture simulations, whilst also offering traditional (third generation techniques) used for the assessment of chief executive potential. By using these ‘fourth generation’ methodologies the authors believe the CIMD is able to make a dual contribution to NZPS strategy.