We introduce the idea of a design to detect signals of efficacy in early phase clinical trials. Such a design features three possible decisions: to kill the compound; to continue with staged development; or to continue with accelerated development of the compound. We describe how such studies improve the trade-off between the two errors of killing a compound with good efficacy and committing to a complete full development program for a compound that has no efficacy and describe how they can be designed. We argue that such studies could be used to screen compounds at the proof-of-concept state, reduce late Phase 2 attrition, and speed up the development of highly efficacious drugs.