Psychologists employing digital computers in the laboratory to control experimental procedure must construct programs. A language is described that incorporates many data representations and manipulations useful in presenting stimuli, collecting responses, and deciding the course of an experiment. PSYCHOL is an extension to a subset of ALGOL, with data types extended to include simple lists, strings of text, historic variables, and responses. Timing mechanisms, stimulus presentation, and data recording instructions expand the operations available within the language.