Roots are crucial plant organs providing physical support and facilitating the uptake of water and essential mineral nutrients, such as nitrogen and phosphorus, thereby supporting plant growth. Previous research has extensively investigated variations in root functional traits and their contributions to individual plant growth, community assembly, and ecosystem functioning. However, conventional conceptual frameworks and measurement techniques for root traits have generally constrained research on the organ, individual, and population levels. Consequently, fundamental ecological questions remain unresolved, including the quantification of the abundance of fine roots in plant communities, the relationship between fine root traits and ecosystem functions, and the feasibility of scaling individual fine root traits to the community level. Although previous studies have attempted to scale root traits from the organ to the ecosystem level, existing methods have scale mismatches between traditional functional traits measured at the organ level and ecosystem-level processes. This methodological limitation has constrained our understanding of physiological mechanisms and ecological processes governing trait–ecosystem function relationships. Therefore, developing more effective methodologies to scale root functional traits from the species to the community levels and clearly establish their relationships with ecosystem functions is critically important. Recently, innovative conceptual frameworks and measurement approaches have been introduced for assessing root traits at the community level, offering promising avenues for establishing linkages between root functional traits and ecosystem functions. In this chapter, we explore the historical context, theoretical foundation, and scientific significance of community-level root functional traits. We comprehensively define the concept of root community traits (RCTs), discuss their implications, explain methods of derivation, and identify key parameters. Furthermore, to empirically validate the utility of RCTs, we conducted field surveys along three contrasting grassland transects across the Inner Mongolia, Loess, and Qinghai–Tibet Plateau. Through these surveys, we investigated spatial variations in root functional traits and assessed their capacity to predict grassland productivity patterns across large scales. The novel concept of RCTs addresses previous methodological shortcomings by aligning trait measurements with appropriate ecological scales, thereby enhancing the integration of root traits into ecosystem function studies. However, significant challenges remain regarding methodology and data acquisition for field-based investigations of root community traits. Advanced, nondestructive root-sampling technologies are urgently required to expand the datasets on root community traits and to integrate their multidimensional characteristics, thereby improving the prediction accuracy of ecosystem functions.