This paper studies a method for rotor-resistance adaptation for indirect-field orientated control of induction generators based on a reference model. It will be shown how the adaptation procedure can be made independent of stator frequency and load torque. The stability of the adaptation procedure will be demonstrated by means of Lyapunov theorem. Simulation results using data from two different machines will be presented to validate the main contributions. Finally, the sensitivity of the algorithm to errors in other machine parameters will be investigated.