Organizations increasingly recognize the need to adopt a process orientation as a means of approaching challenges such as globalization, Enterprise Systems implementations or alternative improvement perspectives. A comprehensive understanding of the operational capacity to support and extend BPM strategies is critical to this endeavour. To this end, organizations require appropriate frameworks, which assist in identifying and evaluating their BPM capabilities. The development of maturity models has long been recognized as a means of assessing capabilities within a given domain. However, due to the idiosyncratic structure of many of the more than 150 available maturity models they can not be translated into tools that are embraced and applied by practitioners. To address this issue, the Delphi technique has been adopted during the development of a maturity model for Business Process Management. This paper presents the design and conduct of the Delphi Study series including the major outcomes being definitions of the six factors critical to BPM (i.e. Strategic Alignment, Governance, Methods, Information Technology, People and Culture) and the identification of capability areas whose measurement is seen to be necessary for assessing the maturity of these factors.