Important advances have been made recently in the invention and application of experimental methods to control the sawtooth instability in tokamak plasmas. The primary means of control involves the application of either ion cyclotron resonance heating, or electron cyclotron heating, with resonance very close to the q = 1 radius in the plasma core. Reported here are experiments which have successfully applied these methods in order to either shorten or lengthen the sawteeth deliberately, in a variety of plasma conditions, in three tokamaks: JET, TCV and TORE-SUPRA. It is shown that despite the sensitivity of the sawtooth period to the resonance position, sawteeth can be controlled using either real-time control of the electron cyclotron deposition, or in the case of ion cyclotron heating, very careful adjustment of the magnetic eld strength and minority ion concentration. The latter technique has been guided by theoretical advances which have enabled the control of sawteeth in JET with ITER relevant ICRH scenarios.