SummaryHamerkops were studied in Uganda, mainly in the vicinity of Kampala, during January‐August 1964. Behavioural observations were made of nest‐building pairs, as well as of non‐breeding birds.Locomotion and feeding behaviour are described. Diving take‐offs and landings, essential for entering or leaving a completed nest, are sometimes seen in other situations as well. Birds sometimes forage while on the wing, in addition to the more usual method while wading.The most frequently seen comfort movements and maintenance activities are described. Hamerkops do not excrete onto their legs when over‐heated as do the storks. The resting posture of sitting completely down on horizontal branches, which is common among Hamerkops, apparently is not known in any of the herons or storks.Primarily hostile (Upright and Forward Threat) and primarily sexual (“Yip‐purr”, Nodding and False Mounting) social displays are described. During False Mounting, birds mount their partners repeatedly without making any attempt at copulation; reverse mountings, in which the other partner assumes the top position, are frequent.The large, hollow nest and its construction are briefly described. During the 6–7 week building period at one nest, at least 8000 loads of material were added to the structure. Both members have an equal role in nest‐building, and generally work independently of each other. They showed no stick‐exchange displays as do herons and storks.When all known aspects of the Hamerkop's behaviour are considered, there appears to be little similarity with either the herons or the storks. In fact, present behavioural evidence does not seem to indicate a particularly close relationship with any other