Literatures on intelligence predominantly focus on intelligence failures, often explicitly claiming that the failures reflect the poor performance of the intelligence agencies as a whole. Despite negative claims on the performance of these agencies, politicians, citizens, and scholars often have little to discuss on intelligence performance. They seldom ask what the intelligence services do in aggregate; what their performance rate is; how the infrequent yet prominent failures compare to ongoing performance that is invisible to the outsiders because it is at least adequate; and how ignorance of the performance of the different types of intelligence activities affects the overall assessment of the intelligence services. This little discussion on some of the important aspects of intelligence performance resulted in the absence of general theory of intelligence performance. To judge better intelligence performance, understanding the functions and the nature of work of the intelligence services is a must. This article hence uses existing theory and available data to determine the theory of the whole performance of intelligence agencies. It also provides a scorecard of the recent performance of the U.S. intelligence and suggests avenues for future research.