Assessment practices have been, and are likely to continue to be, a well-integrated part of early intervention and early childhood special education. While our field has sometimes adopted approaches to assessment that seem at odds with best practices, most assessment practices used with young children and their families are intended to provide useful information and contribute directly to intervention design and evaluation. Current activities in research and practice suggest three themes or directions that will mark early childhood special education assessment into the 21st century. First, I expect continued—indeed, intensified—attention to assessment of progress and growth for individuals and groups. Second, methods typically associated with ecobehavioral research will continue to be adapted and refined for practitioners to directly assess a variety of environmental conditions and characteristics that affect young children's performance and development. Third, continued integration and linkage of assessment and intervention practices will yield more formal monitoring and decision making models that will reduce the uncertainty about when and how to intervene. Together, these future directions in assessment practice will contribute directly to improvements in the services and supports provided to children and families and to the outcomes these services and supports produce.