This paper focusses on JET's contribution through experimental and computational studies to solving the ITER divertor problem. Results from detached plasmas in the "Old" JET configuration of 1991 and the new JET pumped divertor of 1994 are presented and compared with numerical simulations based on the EDGE2D/NIMBUS suite of codes. A computational study of detached plasmas is undertaken in the context of the different divertor configurations planned in the JET programme.