My goal is to provide a general introduction to current behavior-analytic perspectives and methodology concerning simple and complex discrimination. My intended audience is broad—professional scientists and clinicians of all disciplines who want an informed introduction to relevant behavior-analytic methods and theory, students who are in the process of becoming professional scientists or clinicians, teachers of behavioral science, and interested nonprofessionals who want to learn something about behavior analysis as a scientific discipline. Given my objectives and intended audiences, I will not try to explain highly technical quantitative theory (e.g., Nevin, Davison, Odum, & Shahan, 2007). Rather, my goal is to present and discuss simple and complex discrimination learning from the perspective of a behavior analyst who has focused on (a) understanding discrimination learning in children and adults with and without intellectual or other developmental disabilities and in certain nonhumans and (b) translating research findings into instructional technology. Thus, I plan to travel a familiar path that has been set out by Skinner (1968), Keller (1968), M. Sidman (1971), and other leading figures of my discipline. (PsycINFO Database Record (c) 2014 APA, all rights reserved)