In deciding between the use of ballasted track or slab track, an important issue is their noise and vibration performance, as slab track is usually considered to be noisier than ballasted track. The comparative performance of different track designs is assessed here in terms of both noise and vibration. The TWINS model is used to predict the rolling noise, including improved models for the influence of ballast absorption. The noise levels from two ballasted tracks and a typical slab track are compared for a common vehicle type, roughness level and train speed. A difference of around 4 dB in the track noise component is found between the two ballasted tracks with different pad stiffnesses. Consequently the total noise level for the case with slab track is around 3 dB higher than that for the ballasted track with stiff rail pads but is only 0-1 dB higher than the level for the one with soft pads. These results are sensitive to some extent to the assumptions made. A comparison is also made between the ground vibration performance of a ballasted track and a slab track using a semi-analytical model. For the same fastener stiffness it is found that there are only small differences, with the mass of the track slab leading to reductions of 1-2 dB at frequencies above 16 Hz. However, if softer rail fasteners are used in the slab track, as is usual, this leads to further reductions above 80 Hz. The critical velocity on soft soil is also considered; although there is little difference between the different tracks for a homogeneous ground, the critical velocity is increased by the slab bending stiffness for grounds with a soft surface layer. The maximum rail displacement is also smaller for a slab track.