Determining the intensity of the Earth's ancient magnetic field strength from palaeomagnetic or archaeomagnetic measurements is a highly complex task. In the last years a wealth of new methods have been developed to improve or simplify, both absolute and relative paleointensity determination. Here we invite experimental and theoretical studies of the underlying methods as well as comparative studies between different techniques to discuss their advantages and shortcomings. We also invite contributions which help to improve our knowledge of the time evolution of the geomagnetic field strength.