The status of current research into the relations between thunder and the lightning process is examined. Nonlinear effects near the discharge strongly influence the pressure waveform and hence the nearfield acoustic spectrum. At distances where measurements are typically made, propagation effects strongly influence the shape of the recorded spectrum. Since most measurements do not reliably determine propagation distances or the physical characteristics of the propagation path, they are of little value in deducing the nearfield pressure waveform. Even with these problems, the gross features of thunder can be explained qualitatively and there is hope that future experiments will provide information necessary to correct for propagation effects making the study of thunder a useful tool for testing theoretical models of lightning.