In three experiments, we examined a new memory phenomenon: disputed memories, in which people dispute ownership of a memory. For example, in one disputed memory each of two twins recollected being sent home from school for wearing too short a skirt, although only one of them was actually sent home. In Experiment 1, 20 sets of same-sex adult twins were asked to produce a memory for each of 45 words, and most twins spontaneously produced at least one disputed memory. In Experiment 2,20 different sets of same-sex adult twins rated disputed memories as higher in recollective experience, imagery, and emotional reliving than nondisputed memories. In Experiment 3, siblings who were close in age as well as same-sex friends were also found to have disputed memories, but less often than twins.