An elementary survey of item characteristic curve theory, centered around the problem of individualized (tailored) testing, is presented. Following the introdcution, discussions are provided of the following: Test Theory for Itemized Tests: The Guttman Scale: Item Characteristic Curve Theory: An Alternative Model: Specialization, Application, and Evaluation: Pretesting: The Statistical Estimation of Ability: A Simpler Procedure for Estimating Ability; Stochastic Approximation; The Staircase Method for Selecting the Test Questions; Scoring the Answers; Evaluation of Testing Methods; and Relation to Psychophysical Methods. An extensive list of references is provided. (DB) (39pp.)