The relation between autonomy support and basic need satisfaction was investigated by applying a longitudinal design at a time interval of two years, and by comparing two different grade level cohorts of students. Participants comprised 1.225 Norwegian students divided by two subsamples (6th and 8th grade level/8th and 10th grade level). The results showed stationary effects of autonomy support and basic need satisfaction, respectively, from Time 1 to Time 2. There was also evidence of a causal effect from T1 to T2 between autonomy support and basic need satisfaction, and reciprocal causation from basic need satisfaction T1 to autonomy support T2. These effects were grade level and gender specific. The present study provided support for longitudinal relations between autonomy support and basic need satisfaction. Autonomy support and basic need satisfaction are both antecedents to and consequences of themselves, also when measured at long term intervals.