Test developers are basically concerned about the quality of test items and how examinees respond to them when constructing/selecting test items. Psychometricians depend on psychometric techniques to determine the validity and reliability of these test items. Two psychometric theories have been theoretically and technologically developed for designing, analyzing, scoring or standardizing test items within measurement frameworks as identified in this book. They are CTT and IRT, the two theories are widely perceived as representing two different measurement frameworks. A standardized examination supposed to possess acceptable item parameters, as it is true that test items parameter is a function in students’ achievement. Are these item parameters satisfactory when the IRT procedure is applied to the West African Examinations Council and National Examination Council, SSCE Mathematics multiple choice test items?. Therefore, this book is aimed at providing empirical evidence of the application of item response theory in item selection. Examination bodies, teachers who are involve in test validation as well as item selection are to benefit from practical application of the theory.