This paper describes the development of an adaptive assessment called Interactive Computerised Assessment System (InCAS) that is aimed at children of a wide age and ability range to identify specific reading problems. Rasch measurement has been used to create the equal interval scales that form each part of the assessment. The rationale for the structure and content of InCAS is discussed and then different formats of feedback supplied to teachers are explained. This feedback is accompanied by research-based strategies for remediation, following the principle of assessment for learning, which promotes the provision of feedback on how to improve.