Professional services are one of the fastest growing industries, accounting for over US$330 billion in revenue, globally. The industry is also characterised by stiff competition among professional consulting firms. Thus, in order to survive and grow sustainably, consulting companies need to, not only deliver high quality services which surpass their clients’ expectations but, also nurture strong relationships with them.This study sought to understand the relationship between project delivery success and the strength of client-consultant relationships. It used the engineering consulting industry, focusing on public sector clients and consulting firms in South Africa. The methodology used focused on first establishing as to whether clients and consultants measure project delivery success and relationships using the same factors. It then tested the relationship between project delivery success and client-consultant relationships using the identified set of factors.Through a detailed literature review, project delivery factors were categorised into project success and project management success factors. In order to capture the different dimensions involved in project delivery and client-consultant relationships, frameworks were developed to adequately classify these factors. These frameworks were used in the design of the data collection instrument.The findings from the study indicated that clients and consultants measure project delivery success using fairly similar factors, which they also rated in a fairly similar way. However, the study established that clients and consultants neither evaluate relationships using the same factors, nor rate the factors in a similar way. It was also found that project delivery success does not necessarily result in strong client-consultant relationships.On the basis of these findings, the study established that product delivery success is results from the interaction of many factors within and beyond project boundaries. It also involves a variety of stakeholders with different expectations. Project success is more difficult to measure than project management success. Client-consultant relationships depend on the types of clients and consultants involved as well as the model of engagement used. These factors also influence the choice and priority given to different measurement factors.Thus, the study recommended the importance of active client-consultant engagement for clients and consultants to and understand these complex context-specific environments in structuring and defining problems and design relevant solutions.