A virtual world is a computer-simulated three-dimensional environment. They are increasingly being used for social and commercial interaction, in addition to their original use for game playing. This paper studies negative behaviour, or ‘griefing’, inside one virtual world through a series of observations and focus groups with users. Data were collected to identify griefing behaviours and their impact, examine why griefing happens and who the likely targets and perpetrators are, and suggest strategies for coping with it. Findings show that griefing behaviour is common. It is defined as unacceptable, persistent behaviour and is typically targeted at inexperienced residents by those with more knowledge of the virtual world. Community and individual coping strategies are identified and discussed.