We present a model of the synchronously mode‐locked cw dye laser which predicts a square root dependence of dye pulse width on pump pulse width and intracavity bandwidth (&ohgr;c). Experiments performed on the Rhodamine 6G laser confirm the &ohgr;−1/2cdependence. For a pump pulse width of 100 ps, subpicosecond dye pulses are obtained for intracavity bandwidths greater than 150 A˚, and the minimum pulse width is shown to be limited by the bandwidth of the dye to ∼0.5 ps.