This paper examines the application of mixed method designs in implementation research across 22 mental health services studies published in peer-reviewed journals over the last five years. The authors found seven different structural arrangements, five functions of mixed methods, and three ways of linking quantitative and qualitative data. The complexity of these designs was influenced by the number of aims or objectives, study context, and phase of implementation examined. The findings provide insights into how mixed method designs can be effectively used in implementation research, offering suggestions for future studies. The paper also discusses the benefits of combining qualitative and quantitative approaches, such as enhancing understanding of implementation processes and outcomes.This paper examines the application of mixed method designs in implementation research across 22 mental health services studies published in peer-reviewed journals over the last five years. The authors found seven different structural arrangements, five functions of mixed methods, and three ways of linking quantitative and qualitative data. The complexity of these designs was influenced by the number of aims or objectives, study context, and phase of implementation examined. The findings provide insights into how mixed method designs can be effectively used in implementation research, offering suggestions for future studies. The paper also discusses the benefits of combining qualitative and quantitative approaches, such as enhancing understanding of implementation processes and outcomes.