This article identifies and unpacks three key decision points in a systematic mixed research synthesis, a mixed methods approach to research synthesis. The research community has increasingly recognized the value of synthesis studies in expanding our understanding of phenomena. Mixed-methodology broadly has also gained ground as a pragmatic approach to research investigations. By leveraging mixed methods approaches in a synthesis review, systematic mixed studies review (SMSR) enables a broad and integrated summary of existing research on the topic. Yet SMSRs can be challenging to undertake given the complexity of working with research synthesis and mixed methods requirements. This methods guidance article presents information to assist novice researchers in navigating these critical decisions in SMSRs, and provides examples of how these were addressed by researchers in the two case studies provided. Implications of the SMSRs for the research community and future research directions are also discussed.