Integrated modelling and environmental decision support are increasingly important as society tackles some of the most complex challenges of our generation, with impacts on future generations. When integrated modelling is successful, the results can be transformational yet the core elements for generating that success are not always clear. There is an elusive element to finding the best mix of methods, models and approaches for any given problem. This raises issues for repeatability and questions regarding how the emerging metadiscipline will converge in order to consistently achieve quality results or increased understanding of the processes that lead to success. Key challenges include the need to diagnose elements that lead to successful process, training for professional and technical competencies, and increased access to stable platforms and interchangeable models and modelling tools. This paper aims to summarize some of the key process and product related challenges of integrated modelling and environmental decision support.