Paradoxical performance effects (‘choking under pressure’) are defined as the occurrence of inferior performance despite striving and incentives for superior performance. Experimental demonstrations of these effects on tasks analogous to athletic performance and the theories that may explain them are reviewed. At present, attentional theories seem to offer the most complete explanation of the processes underlying paradoxical performance effects. In particular, choking may result from distraction or from the interference of self-focused attention with the execution of automatic responses. Experimental findings of paradoxical performance decrements are associated with four pressure variables: audience presence, competition, performance-contingent rewards and punishments, and ego relevance of the task. The mediating factors of task complexity, expectancies, and individual differences are discussed.