A high-quality, age-appropriate transition assessment is a foundational component of effective transition planning for students with disabilities. In accordance with the Individuals with Disabilities Education Act (IDEA), transition services must be based on assessment data that accurately reflect the student’s strengths, preferences, interests, and needs. To achieve this, it is essential that IEP teams utilize a wide range of both formal and informal assessment tools, including interviews, observations, standardized instruments, questionnaires, and performance-based measures. Collecting data from multiple sources over time ensures a comprehensive understanding of the student’s current levels of functioning and postsecondary aspirations. This evidence-based approach not only supports the development of meaningful and measurable postsecondary goals, but also informs the coordinated set of transition services and activities that are legally required to facilitate the student’s movement toward further education, employment, and independent living. This section outlines best practices for implementing robust transition assessments and integrating their results into the individualized transition planning process.