Ethological observations of the introduction of new charges into a large mixed-sex group in a dog shelter, and the later behaviour of the dogs in the run, were used to investigate a method of early assessment of the dogs’ reactions to the new situation. Subjects were divided qualitatively into four categories according to their interactional behaviour during the first two days (‘dog-oriented’, ‘human-oriented’, ‘dog & human friendly’, ‘asocial’). This classification was compared to an independent division resulting from statistical analysis of the dogs ‘ entry-sequences, and was found to be consistent for 80 per cent of dogs. One week after entry, both female and male dogs received distinctively fewer social interactions by conspecifics and tended to direct more interaction-initiating behaviour towards the keeper, thus demonstrating an integration process; females became more physically active and initiated significantly more interactions with other dogs; for males, the contrary was found. Qualitative comparison between first visitors and regular guests suggest that experienced dogs integrate faster, showing fewer behavioural signs of distress and engaging more often in investigatory behaviour. Results indicate that the assessment of dogs from their behaviour during the entry-sequence is a valid method to predict later tendencies. Males and females should be handled differently during introduction. The stress of entry into an existing group can therefore be reduced, improving the animals’ welfare.