The report describes tracking systems which address the need for early, reliable, and consistent identification and follow-up for children at risk for developmental disability. The systems, developed by 15 states that participated in the "Project Zero to Three" network, demonstrate how states may approach the linkages among prevention, early identification, and early intervention services. The efforts and strategies of the 15 states reflect the diversity of approaches, philosophies, systems, and state initiatives to identify infants at risk and to assist their families in locating and accessing early intervention and health care services. Discussed are goals of a tracking system, cost versus benefit of a tracking system, criteria for inclusion, criteria for discharge, instruments and techniques needed for optimal tracking and linkage to services, agency responsibility, and the role of parents. Appendices provide, for each of the 15 states, an outline of the system's purpose, a description, a discussion of issues/barriers, plans for the future, and sample forms. The 15 states presented include: Florida, Hawaii, Iowa, Kansas, Maine, Maryland, Massachusetts, New Jersey, New York, North Carolina, Ohio, Oregon, Texas, Utah, and Washington. Includes 15 references. (JDD)