Development of a caretaker-report instrument of the assessment of infant temperament is described, and longitudinal findings are reported. Temperament dimensions were selected for investigation from the work of Thomas, Chess, et al, Escalona, Diamond, and others. Conceptual analysis of scale definitions was carried out to eliminate conceptual overlap of scales, and item analysis was performed for 463 Infant Behavior Questionnaires for out for 3-, 6-, 9-, and 12-month-old subjects.  Scales with adequate psychometric and conceptual properties were developed for the following dimensions activity level, soothability, fear, distress to limitations, smiling and laughter, and duration of orienting. In longitudinal analyses, activity level and smiling and laughter scales revealed stability from 3 through 12 months, duration of orienting and soothability showed less general stability, and fear and distress to limitations showed stability only beyond the age of 6 months. (author abstract)