Facet Benchmarking is a psychometric method that contributes to the measurement and conceptualization of abstract psychological constructs. An instrument refinement method, Facet Benchmarking sets out to optimize measurement accuracy by identifying redundant and extraneous facets. This chapter explains the method, describes its process and methodological considerations, and presents relevant findings from mindfulness research. Implications of Facet Benchmarking for mindfulness are elaborated, including future directions for research and measurement.