Abstract
Under conditions of intensifying strategic competition, great powers and less-than-great powers alike are reappraising their national-security strategies. Central to such reviews are assessments of power and strategic advantage - in an era of great-power competition, states need to know who is winning. This is the function of strategic net assessment, recently revived in the United Kingdom through the Secretary of State's Office for Net Assessment and Challenge. This paper sets out the conceptual challenges involved in making assessments of power, considers the main historical efforts to do so, and offers some practical guidance as to how strategic net assessment may be used to inform strategy.