This paper outlines the principles of operation and some areas of application of two electronic control systems developed by Bomag to optimize the use of compaction equipment on earthworks, sub-base and bituminous materials. The first is a compaction control system known as the Terrameter and is designed to provide continuous information about the state of compaction of earthworks and sub-base materials whilst rolling is in process. Secondly, a speed and vibration control system is described whereby rolling speed, the rate of acceleration and deceleration, and the vibration functions are controlled electronically.