The development of trauma-informed child welfare systems (TICWSs) that advance individual agency practice to target transformation of the system as a whole has been conceptualized but not documented. A grassroots effort to build a TICWS with key participants (e.g., Department of Human Services, Community Mental Health, Family Court, schools) in nine Michigan communities provides a field tested model for implementation. This article described what emerged as the core elements for a TICWS, which includes (1) development and support of a project champion, (2) trauma identification, (3) comprehensive assessment of traumatic impact, (4) evidence based trauma treatment, (5) establishing a common trauma language, and (6) trauma-informed decision-making. Several new instruments for assessing a TICWS are identified. Lessons learned are highlighted for consideration of communities seeking to develop TICWSs. (Contains 2 tables and 1 figure.)