This study aimed at providing people dealing with developmental disabilities with web-based assessment application. it also aimed at supporting people dealing with developmental disabilities by providing them scientific, effective, and exact assessment instrument on-line. The results of the study showed as follows. Fist, the assessment program developed in the study provides a definite on-line system to assemble all the available data on each individual`s assessment. Second, it offers clear and definite methods for construction web-based assessment instruments. Third, it proves cost-effectiveness in terms of saving time, convenient recording, effective management, and exactness of its result. Fourth, it offers the base of Facilitating its standardization and of development of further assessment instruments.