Military power is central to diplomacy and much of international relations, yet common quantitative measures have limited surface validity. This limitation stems from focusing on latent power and only indirectly incorporating major weapon systems. I contend that weapons are central to military power and present a new measure of country military power based primarily on armaments. The measure includes major naval, air and land weapons as well as nuclear weapons and ballistic missile capability. I examine the surface, content and context validity of the measure and compare it to existing measures. I show that this measure of material military power (MMP) has more surface and context validity than alternative measures. I find that MMP better predicts war outcomes, better accounts for militarized threats, and performs well as a control variable for country power.