The relationships between contaminant removal from impervious pavements and raindrop impact energy, cumulative kinetic energy of rainfall events, and rainwater fit were evaluated. A commercial urban area was chosen to perform simulated rainfall experiments. The runoff from these experiments was collected and analyzed for total suspended solids, volatile suspended solids, total Kjeldahl nitrogen, soluble Kjeldahl nitrogen, oxidized nitrogen, ammonia, ortho-phosphate, total phosphorus, soluble phosphorus, total lead and total zinc. Raindrop impact energy, rainfall intensity, rainfall duration, and rainwater pH were factors which were varied to examine their effect on contaminant wash-off phenomena. The present exponential decay theory of contaminant removal was verified and modified to incorporate the cumulative kinetic energy of rainfall events. An empirical model for contaminant removal was also developed. Data showed that both raindrop impact energy and cumulative storm energy had significant effects on contaminant removal. Contaminant wash-off was found to be independent of rainwater pH except for solids removal at low rain intensities. Additional results indicated that there is a "threshold impact energy" necessary before significant removal of contaminants associated with insoluble material can occur. The kinetic energy attributed to surface runoff overflow was found to be very important in the mechanisms responsible for contaminant removal at high rainfall intensities.