Aerial, shipboard, and underwater observations were made during Spring of 1976 of the population of humpback whales, Megaptera novaeangliae, breeding in Hawaiian waters. Animals were found around all of the major islands, almost always within the 100 fathom contour, with the bulk of the population concentrated in regions having the greatest contiguous extent of such water. Breeding and calf rearing were not confined to any given area. Survey results yielded estimates of from 200 to 250 animals. The birth rate was estimated as less than 10%, a low figure of some concern. Coloration characteristics of the Hawaii population differed considerably from the eastern North Pacific population of humpback whales, suggesting little genetic exchange with that group. Differences from the western North Pacific group were less clear, in part because of sparsity of data. Approximately 18% of the animals were alone when observed; the remainder were in pods of 2 to 9 animals. Overall there were considerably fewer singletons and considerably larger-sized pods than has been observed in feeding ground aggregations. A calf was typically found in a multiple animal pod, consisting of the mother and, most frequently, one other adult "escort whale". The escort seemed to serve a protective function. The large majority of the pods were swimming in fairly regular formations in apparent local migratory movements. Milling pods, with animals contacting one another, or engaging in other behaviors seemingly consistent with sexual courtship or advertisement,was observed in 16% of the cases. The possibly adverse effects of increasing public and commercial on-water and in-water whale watching activities on the reproductive success of the whales was noted.