Two aspects of continuity, stability of individual differences and means, were examined in a longitudinal study from the middle elementary through the high school years. Two hypotheses regarding individual-difference stability were supported with structural equation modeling in both the general-verbal and math domains: (a) Academic intrinsic motivation is a stable construct throughout these years, and (b) with advancement in age, academic intrinsic motivation becomes increasingly stable. A third hypothesis, that the mean level of academic intrinsic motivation declines over these ages, also was supported, and significant linear trends were obtained, but it was also found to be modified by particular subject areas, with math showing the greatest decline and social studies showing no significant change. The combination of these 2 aspects of continuity places those with low motivation early in their schooling particularly at risk.