In this study, we analysed the effects of social and human contact on calves' behaviour and stress responses. We also measured the effect of this contact on calves' reactions to novel conspecifics and novel humans. Sixty-four calves were housed either alone or in pairs and received either minimal human contact or 'additional' human contact (stroking and talking). At six, 10 and 14 weeks of age, the behaviour of the calves was recorded in their home pens. Calves were then tested in an unfamiliar arena either alone, with an unfamiliar calf or with an unfamiliar man, and in a Y-maze with one arm leading to a calf and the other to a man. An adrenocorticotrophic hormone (ACTH) challenge was performed in order to assess chronic stress responses. Compared with individually housed calves, pair-housed calves were more active and made fewer contacts with their neighbours when in their home pens; they were also less active in the arena, spent more time near the calf in the Y-maze, and had lower cortisol responses to ACTH. Calves that had received additional human contact interacted more with the man in the arena and had lower mean heart rates than those that had received minimal contact. This study confirmed that calves feel a need for social contacts and that pair-housing can lower the stress felt by calves separated from their conspecifics. Additional contact from stockpersons increases calves' likelihood of approaching humans but cannot compensate for their lack of social partners. Hence, when calves are separated, the duration of the separation should be limited, and visual and physical contact with other calves should be provided.