Method for processing converted mode seismic data. Compressional and converted compressional to shear wave data is acquired by generating compressional energy into a subsurface formation and recording the amplitude of reflections as a function of time at spaced locations along a line of exploration. A series of compressional to shear wave velocity (Vp/Vs) ratios are selected based on an analysis of the acquired seismic data and the shear wave velocity for each Vp/Vs ratio is determined according to the following relationship: ##EQU1## where k=Vp/Vs. Data corresponding to each Vp/Vs ratio is stacked together, the series of stacks are correlated to the originally acquired seismic data to determine the actual Vp/Vs ratio for the formation and the shear wave velocity is derived. The originally collected data is then corrected for normal moveout and stacked.