Now more than ever, the pulsed power field is driven by size, weight, and volume constraints. In both the military and commercial arenas, there is an overwhelming need to provide more and more capability in ever smaller and lighter packages. The need for higher energy density, power density, reliability, and efficiency is driving progress in the field. This paper provides a review of the state of the art in various types of pulsed power components such as solid-state switches, capacitors, and power sources. In some cases, familiar components such as switch tubes are being replaced with whole new classes of devices. Batteries are being replaced by hydrocarbon or hydrogen-fueled mechanical systems that alter our paradigm for prime power sources. Trends over the past few years and future possibilities for ultracompact systems are discussed, including advanced techniques for heat removal and energy recovery. Finally, a few practical examples of ultracompact systems are given, emphasizing peak power and peak power density.