This paper presents a new technique for determining the optimum settings of the conventional two-mode and three-mode controllers. The procedure which utilizes the practically available on-line closed loop data is an extension of the classical work of Ziegler and Nichols (1942). The advantages of the present method over that of Ziegler and Nichols are (i) that it does not require the process to undergo sustained oscillations, (ii) that the tuning constants are determined iteratively (and not by hit-and-miss technique) thereby making the tuning adaptive in nature and (iii) that it is possible to select a criterion of optimality other than the usual 1:4 decay ratio.