This article outlines the process of developing a quantitative instrument and livelihood asset index. The intent of the index was to assess household perspectives of the impact of the removal of explosive remnants of war on livelihoods. Conducted in the Lao People’s Democratic Republic, the study used a sequential mixed methods design. It began with a qualitative component, which informed instrument development. The article discusses the instrument development process and some of the challenges faced. These included developing a reliable livelihood asset index and finding the limitations of quantitative indexes in this setting. Another challenge was reconciling tensions in mixing methods informed by different worldviews.