The aim of this chapter will be to make a detailed exploration of mixed methods research (MMR) designs as an indicator of a movement towards more complex and innovative research designs in which both qualitative and quantitative approaches are combined, integrated, fused and blended. The MMR movement has now developed to a stage where there are over 40 MMR designs and even typologies of typologies. The two-dimensional linear concept of triangulation, so often used in pure quantitative mono-methods research or in qualitative research as a measure for validity, has become a thing of the past for those utilising MMR. There is also a significant amount of cross-fertilisation between the disciplines within the MMR community with the following disciplines all contributing to methodological advances in MMR design: health, nursing, medicine, business/management, education, engineering and psychology/counselling. The usefulness of conducting MMR in trans-disciplinary teams will become apparent to organisational project management researchers through the discussion of complex and novel MMR designs. MMR is useful when a phenomenon being studied is complex and needs multiple methods to investigate it. MMR has been found useful in a variety of fields and applications including management and organisational research but does not seem to be prominent in project management (PM) research despite the need for investigating better approaches to deal with complexity in projects. The authors of this chapter feel that a discussion about MMR will make a useful contribution to a book promoting translational approaches in PM research by assisting PM researchers to study complex phenomena.