This study investigates decision-making processes used by South Australian Project Management Offices to select and engage professional consulting services. A range of published literature was examined to determine the extent to which decision-making processes and inputs have been documented to date; the review found that while the literature discusses a variety of client-consultant interactions, it is typically viewed from a post-selection context, and provides little evidence-based examination of the decision-making factors that precede such engagements. Research into this topic was conducted by interviewing 8 project management professionals from different industry backgrounds and employment arrangements. The factors and relationships described were used to develop and promulgate a decision-making framework. Client organisations are anticipated to find this framework useful when establishing the most appropriate resourcing arrangements of their projects, or in making more generalised decisions around their use of consultant services. Consultants are also anticipated to find value from this framework as it will provide a useful reference-point of client engagement motivators and processes.