A 2×3 study, using performance on a pseudo concept formation task as the dependent variable, tested the efficacy of covert extinction (CE). Groups received either CE instructions, overt extinction (OE) instructions, or no instructions, and either reinforcement or no reinforcement. The data revealed no significant difference between the unreinforced CE and OE groups, but did indicate significant differences between these groups and the unreinforced group receiving no instructions. Parallel results were obtained for the three similar reinforced groups. The conclusion, based on these data, was that CE was effective in facilitating the course of extinction whether or not the environment continued to provide reinforcement for the specific response. © 1974.