On 15 June 1963 and 16 June 1964 F. E. Ludwig and I found a pair of Ring-billed Gulls (Larus delawarensis) nesting within the colony of Caspian Terns (Hydroprogne caspia) at Gull Island in Georgian Bay, Ontario. In 1963 we found an empty nest, but in 1964 the the nest and one eight day old chick were found. The tern colony was on the gravel-limestone ridge at the south end of the island. In both years the gull nest was about five feet within the tern colony which was about forty by seventy-five feet and supported 175 and 185 pairs of terns during the two years. The nearest Ring-bill colony was at Papoose Island, 5.4 miles to the west, where there was also a small colony of Caspians both years.