Errorless learning refers to a variety of discrimination learning techniques that eliminate or minimize responding to incorrect choices. This article describes experimental roots of errorless learning and applied errorless strategies. Specifically, previous research on stimulus fading, stimulus shaping, response prevention, delayed prompting, superimposition with stimulus fading, and superimposition with stimulus shaping are discussed. Educational applications for children with Pervasive Developmental Disorders (PDD) are presented for each technique so that school psychologists, educators, and teachers working with children with PDD can understand the underpinnings and practical applications of errorless techniques to use in skill acquisition programming in school settings. (Contains 1 table.)