Abstract: A method of and device for machining workpieces on a multi-tool machine provided with a numerical control system. For the automatic, simultaneous execution of machining instructions which relate to the control of more than one tool, instruction groups are formed from machining instructions which can be simultaneously executed on the basis of their mutual independence. Within an instruction group, partial dependency can exist, on the basis whereof a subsequent instruction is executed, after a condition imposed in a previous instruction has been satisfied.