OBJECTIVE:Chile is considering expanding its system for early childhood development to include 5- to 7-year olds, but it has no consensus about how to identify at-risk children. This study facilitated a process for incorporating local priorities and best practices to choose a child assessment instrument. METHODS:Using the priority-setting method of the Child Health and Nutrition Research Initiative (CHNRI), 21 Chilean experts defined and weighted ideal assessment instrument characteristics; 130 instruments were scored according to how closely they matched experts' ideal definitions. Instruments were ranked by score under different inclusion criteria. RESULTS:Experts weighted instrument quality highest (95 on 1-100 scale), followed by administration site (87), domains assessed (82), cost (80), administrator (76), Spanish version (75), time (75), and prior use in Chile (53). Experts agreed that an ideal instrument (1) would reliably assess language, socioemotional well-being, mental health, and parenting abilities, (2) could be administered at schools or home, and (3) could be administered by teachers or parents. No single instrument matched all Chilean priorities. Three instruments met 11 of 13 priorities (age; quality; administration at school, home, or waiting rooms; assess language and socioemotional domains; administered by teachers, parents, or psychologists; time ≤30 minutes). Including mental health or parenting abilities ranked instruments whose composite scores were 35% lower. CONCLUSION:Decisions about how to assess children at developmental risk should be informed by local context. The CHNRI method provided a useful process that made explicit mutually exclusive priorities, quantified trade-offs of different assessment strategies, and identified 3 of the instruments that best met local needs and priorities.