鈥� The question, "How well do people remember life changes?" was approached in a longitudinal study of nearly 400 healthy men in a responsible profession. Three scales for assessing life changes were administered by questionnaire at two examinations nine months apart. The subjects were asked to report life change events occurring during a specific six-month period鈥攖hat which immediately preceded the first examination. For all three life change scales there was substantial forgetting over the interval between reports, with a second report yielding total scores 34% to 46% less than those from the first report for the same period. The amount of change over time varied greatly across persons. These findings raise serious questions about the validity of retrospective studies of life change and illness when the period being reported is greater than six months in the past. They do not, however, jeopardize the potential of the method for prospective studies.