Three-dimensional lightning mapping observations have been used to estimate the peak source powers radiated by individual VHF events of lightning discharges. The peak powers vary from minimum locatable values of about 1 W typically up to 10--30 kW or more in the 60--66 MHz passband of the receivers. An energetic positive bipolar event radiated in excess of 300 kW peak power. The strongest radiation sources tended to be observed in the upper part of storms, corresponding to the upper positive charge region, where the breakdown is of negative polarity. The results illustrate the bidirectional nature of intracloud discharges, with the largest source powers being along the negative portion of the discharge and an order of magnitude greater than the source powers along the positive portion. Overall, the source powers follow an approximate P-1 distribution for powers above about 100 W. The radiation sources indicate the location of the main charge regions in a storm; sample comparisons with radar data show that the main negative charge coincided with the precipitation core ¿ 2001 American Geophysical Union