Abstract: Process for temperature-dependent actuation of a supplemental pressure medium source in slippage-controlled motor vehicle braking systems. The invention pertains to a process for operating a slippage-controlled motor vehicle braking system with regulation of driving dynamics. In such systems it has thus far been proposed to turn on supplemental pressure medium sources to support the supply pump when regulation starts, in order to shorten the regulation time. Practical studies have shown that such supplemental sources are, first of all, not needed for each regulation process and, second, cause disruptive noise. The invention thus proposes to turn on the supplemental pressure medium source only in the presence of special situations, such as if the pressure medium is very viscous due to low temperatures. Advantageous refinements are concerned with determination of the temperature.