This policy brief examines states' experiences and data regarding implementation of the transition planning mandate of the Individuals with Disabilities Education Act. It reports on a study which investigated whether implementation of transition planning was associated with decreased dropout rates for youth with disabilities and whether the format for reporting on how special education students exit the system should be revised. Transition related data from the Department of Education were analyzed and interviews were conducted with state-level special education personnel in three states with relatively high school completion rates for their students with disabilities. Data analysis indicated that a previously increasing dropout rate began to decline with mandated transition planning for youth ages 16 and above, but not for youth 14-15 years old, which continued to climb. These results support the value of transition services beginning at age 14. The experiences of the three states support the value of transition planning and services as a component of each student's individualized program. The report also includes graphs showing trend data in the dropout rate for youth with disabilities ages 16 to 21 and ages 14 to 16. (Contains 13 references.) (DB)