This article is a commentary for the special issue on the Early Development Instrument (EDI), a community tool to assess children's school readiness and developmental outcomes at a group level. The EDI is administered by kindergarten teachers, who assess their kindergarten students on 5 developmental domains: physical health and well-being, social competence, emotional maturity, language and cognitive development, and communication skills and general knowledge. In this commentary, the author critically integrates research findings from projects that used the EDI to assess children's development at a community or population level, as presented in the research articles of this special issue. In addition, the EDI is situated in the school readiness literature, and forthcoming research directions and challenges that will largely determine the risk-benefit ratio of the EDI are discussed in regard to the following 3 topics: the advantages and limitations of using teacher judgment for the EDI, the establishment of the EDI's reliability and validity at a group (community, population) level, the EDI's effectiveness for intervention and program evaluation and measurement.