This study explores the stability of temperament, measured by maternal report, from infancy to 8 years in a longitudinal sample of 450 children. Prior questionnaire-based, factor-analytic studies of stability have usually assumed that temperament dimensions show continuity during development and that, where the same temperament factors emerge at multiple measurement occasions, the factors show measurement equivalence. Structural equation modeling was used to test these assumptions. Approach, Irritability, Cooperation-Manageability, Inflexibility, Rhythmicity, and Persistence factors showed substantial continuity from infancy to 8 years. The levels of stability found were substantially higher than has generally been reported. Approach and Rhythmicity showed the highest stability over the full age range, whereas Inflexibility showed the highest absolute level of stability.