This booklet explores how a synergy between assessment and instruction can be forged to enhance student outcomes, especially for students with disabilities. The booklet defines and discusses assessment that enhances instruction, provides an overview of important criteria for judging the utility of this type of assessment, describes previous efforts within special education to link assessment and instruction to improve teacher planning and decision making, discusses strengths and limitations of these methods, introduces performance assessment as an approach for strengthening the connection between assessment and instruction, offers a case study illustrating a teacher's use of performance assessment during instructional decision making, discusses how performance assessment addresses the criteria for ensuring a tight connection between assessment and instruction, and notes key areas requiring additional development and research. (Contains 35 references.) (JDD)